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UNITED STATES COAST GUARD AUXILIARY 

Department of Education 












































GLOSSARY OF 
MARINE TERMINOLOGY 






GLOSSARY 

OF 

MARINE 

TERMINOLOGY 


UNITED STATES COAST GUARD AUXILIARY 

Department of Education 


EDITOR 


Virginia L. Knudsen, DVC-ES 


^JffiCHNICAL REVIEW 



Maxim, DVC-ED 
Bills, BC-EOB 
. Shade, BC-ALC 


EDITORIAL REVIEW 

Vivian E. Siegfried, BC-ESR 


\JZ3 

.657 


TECHNICAL GRAPHICS 
Philip H. Lipstate, Jr., BC-ESP 


Copyright© 1991 

Coast Guard Auxiliary National Board Inc. 
Washington, D. C. 

All rights reserved 


This book, or any part thereof, may not be reproduced 
without written permission of the copyright owner. 

Library of Congress Catalog Card Number: 91-66448 
ISBN 0-930028-07-4 

Printed in the United States of America at no cost 
to the United States Government or 
United States Coast Guard. 

We thank the following 
for his support of this publication: 

Eric Price, Computer Consultant, Vero Beach, FL 








IV 





CONTENTS 


Contents.v 

Preface.vii 

Glossary of Nautical Words/Terms. 1 

Selected Symbols, Acronyms & 

Abbreviations of U.S. Coast 

Guard Auxiliary.91 


v 
















































PREFACE 


One author's gybe is another's jibe. Old salts will know 
the two words are interchangeable, most boaters will not. 
Since our aim is to educate the boating public, not confuse 
them, we have created this glossary of the more common 
nautical terms as a reference tool for members of the Auxil¬ 
iary and students alike. 

This glossary is intended to be a living document. As 
older terms fall into disuse; i.e. parrot perch —a short 
spreader or strut on a mast to spread a stay—and new ones 
become common; i.e. Jet Ski —a brand name of the 
Kawasaki Corporation, commonly used to refer to a personal 
watercraft, this glossary will be periodically revised. 

We have not attempted to include all terminology used 
in “salt speak,” nor is this document intended to be a nautical 
dictionary. The nautical terminology used herein are those 
words and phrases found in our course materials, with the 
definition(s) appropriate to the context of the course. 

We sincerely hope this glossary is helpful to all who may 
find a use for it. 



Department of Education 


vii 




















A 


abaft 

Toward the rear (stem) of the boat. Behind. 

abeam 

At right angles to the keel of the boat, but not on the boat. 

aboard 

On or within the boat, 
above deck 

On the deck (not over it -- see ALOFT), 
abreast 

Side by side; by the side of. 

absolute accuracy 

Term often used in connection with loran system to mean 
the difference between the loran’s estimate of position and 
the actual position. Also called geodetic accuracy. Within 
the coverage area, the absolute accuracy of loran-C is 0.25 
NM or better, 
acquisition 

The reception and identification of transmitted loran-C 
signals from master and selected secondaries to permit 
reliable measurement of TDs. The requisite signal-to- 
noise ratio for original signal acquisition is generally 
greater than for tracking (qv). 
additional secondary factors 

Land path factors due to variation in the conductivity of the 
earth’s surface that alter the speed of propagation of loran 
signals over land compared to over water. ASFs degrade 
the absolute accuracy of a loran system (unless compen¬ 
sated for) but do not affect the repeatable accuracy, 
adrift 

Loose, not on moorings or towline. 

advanced LOP 

A line of position which has been moved forward, parallel 
to itself, along a course line to obtain a line of position at 
a later time. If the same procedure is followed to move the 
line to an earlier time, the LOP is said to be retired. 

aft 

The stem or back of the vessel, 
agger (see double tide) 





agonic line 

The imaginary line connecting points of zero variation. 

aground 

A vessel touching or fast to the bottom, 
ahead 

In a forward direction. 

Aid To Navigation (ATON or NAVAED) 

Any device external to a vessel or aircraft specifically 
intended to assist navigators in determining their position 
or safe course, or to warn them of dangers or obstructions 
to navigation, 
alee 

Away from the direction of the wind. Opposite of wind¬ 
ward. 

align 

To place object in line. 

aloft 

Above the deck of the boat. 

alternating light 

A rhythmic light showing light of alternating colors, 
altocumulus clouds 

“Piled up” clouds at middle altitudes. 

amidships 

The center of the boat with reference to its length or 
breadth. 

anchor alarm 

Feature of many loran-C receivers that can be set to warn 
the user that the vessel has moved outside the swing circle 
of the anchor. This is also termed an anchor watch. 

anchor bend 

A most secure knot for bending a line to an object, 
anchor rode (see rode) 
anchor scope (see scope) 
anchorage 

A place suitable for anchoring in relation to the wind, seas 
and bottom; and permitted by regulations. 

anchorage mark 

A navigation mark which indicates an anchorage area or 
defines its limits. 




A 


anemometer 

A device which measures the velocity of the wind. 

angle of cut 

The smaller angular difference of two bearings or lines of 
position. See also crossing angle. 

annotation 

Any marking on illustrative material for the purpose of 
clarification, such as numbers, letters, symbols, or signs. 

annual inequality 

Seasonal variation in the water level or current, more or less 
periodic, due chiefly to meteorological causes, 
apogean tides or tidal currents 

Tides of decreased range or currents of decreased speed 
occuring monthly as result of the Moon being in apogee 
(farthest from the Earth), 
apogee 

Point in the lunar cycle when the moon and the earth are 
farthest apart. Tides have decreased range when the moon 
is in apogee. App .,.nt 

apparent wind w o* + 

The wind perceived in a moving boat which vv "*\ \ 
is the resultant of the true wind and the wind \ Y\ 

of motion and is always forward of the true wind. ]H 
arc measure \U 

The angle included between radii connecting the 
ends of an arc with the center of the circle of which it is 
a part. 

arc of visibility 

The portion of the horizon over which a lighted aid to 
navigation is visible from seaward. 

armed lead 

A weight which has a hollowed bottom and is filled with 
tallow, grease, wax, chewing gum, or bedding compound 
to bring up a sample of the bottom. 

articulated beacon 

A beacon-like buoyant structure, tethered directly to the 
seabed and having no watch circle. Called articulated light 
or articulated daybeacon, as appropriate. 


3 





A - 

assigned position 

The latitude and longitude position for an aid to navigation. 

astern 

Direction of movement, opposite of ahead; toward a vessel ’ s 
stem. 

athwartships 

Across or at right angle to the centerline of a boat; rowboat 
seats are generally placed athwartships (thwarts). 

aural null 

A null dectected by listening for a minimum or the com¬ 
plete absence of an audible signal. This null as received by 
a radio direction finder indicates that the plane of its loop 
antenna is perpendicular to the direction of the radio wave, 
automated notices to mariners system 

Computer system that can be accessed by authorized users 
to obtain chart corrections and notices to mariners. Users 
need a teletype, computer terminal, or other device, and an 
access code available from DMA. 
autopilot 

Device for automatic steering of a vessel. Depending on the 
sophistication of the autopilot, these can be used to main¬ 
tain a heading, or to interface with a loran or other elec¬ 
tronic navigation system. Sometimes informally called 
“George” or “Iron Mike.” 
avast 

A nautical command to stop, 
aweigh 

The status of an anchor as it just clears the 
bottom when being raised. 

axis of rotation 

The imaginary line connecting the poles 
of the earth and on which the earth 
supposedly spins or rotates. 

B 



back range 

A range observed astern, particularly one used as guidance 
for a craft moving away from the objects forming the range. 


4 




- B 

backstay 

Standing rigging (non movable) that supports the mast 
from aft to keep it in an upright position. Running backstays 
(always in pairs) perform the same function, but may be 
quickly slackened to avoid interfering with the boom. 

backwind 

When wind is deflected from one sail to the lee side of 
another sail, as when the jib is back winding the main. 

ballast 

Heavy material placed in the bottom of a boat to improve 
stability. 

bar 

A ridge or mound of sand, gravel, or other unconsolidated 
material below the high waterlevel, especially at the mouth 
of a river or estuary which may obstruct navigation. 

bare poles 

When a sailboat is underway with no sails set. 

bare rock 

A rock that extends above the mean high water datum in 
tidal areas or above the low water datum in the Great Lakes. 

See also rock awash, submerged rock. 

barometer 

An instrument for measuring the air pressure. 

baseline 

The segement of a great circle that joins the master and a 
secondary station in a loran chain. 

baseline extension 

The extension of the baseline beyond the two joined 
stations. Loran positions in baseline extension areas are 
problematic and ambiguous. 

batten 

A thin semi-rigid wood or plastic strip inserted in the leach 
of the sail to provide support for the sail material. 

batten down 

Secure hatches and loose objects both within the hull and 
on deck. 


5 




B - 

bay 

A recess in the shore, or an inlet of the sea or lake between 
two capes or headlands, that may vary greatly in size but is 
usually smaller than a gulf but larger than a cove. 

beacon 

A lighted or unlighted fixed aid to navigation attached 
directly to the earth’s surface. (Lights and daybeacons both 
constitute “beacons.”) 

beam 

The greatest width of the boat, 
beam sea 

Waves act directly on the vessel’s sides (coming from 
abeam) and, in rough water, could roll some boats over on 
their side. Commonly known as “in the trough.” 

bear 

To “bear down” is to approach from windward, to “bear 
off’ is to sail away to leeward; to bear hand is to help out 
with a task. 

bearing 

The horizontal direction of a line of sight between two 
objects on the surface of the earth. 

beat 

To sail to windward, generally in a series of tacks. 

Beating is one of the three points of sailing, also 
referred to as sailing “close-hauled” or “by the 
wind.” 

becalmed 

Having no wind to provide movement of the 
boat through the water. 

becket 

A looped rope, hook and eye, strap, or grommet used for 
holding ropes, spars, or oars in position. 

before the wind 

Traveling in the same direction toward which the wind is 
blowing; sailing before the wind is called running, 
belay 

To make a fine fast, also a command to stop. 

bell 

A sound signal producing bell tones by means of a hammer 
actuated by electricity or, on buoys, by sea motion. 



6 




below 

Beneath or under the deck. 

bend 

To attach a sail to a spar. Also used as a term to describe a 
knot which fastens one line to another or a line to an object. 

bifurcation 

The point where a channel divides when proceeding from 
seaward. The place where two tributaries meet. 

bight 

1. A long and gradual bend or recess in the coastline which 
forms a large open receeding bay. 2. A bend in a river or 
mountain range. 3. A loop or slack part in a rope. 

bilge 

The lowest spaces in a vessel’s hull. 

binnacle 

A stand holding the steering compass. 

binocular 

An optical instrument for use with both eyes simulta¬ 
neously. 

bitt 

A heavy and firmly mounted piece of wood or metal used 
for securing lines. 

bitter end 

The end of a rope or cable. 

blanket 

To deprive a sail of the wind by interposing another object. 

blink 

An indication that the master or secondary signals in a loran 
chain are out of tolerance and not to be used. Loran 
receivers have a blink alarm that warns the user that the 
indicated positions may not be reliable. Blink conditions 
warn that the signal power or TD is out-of-tolerance 
(OOT) and/or that an improper phase code or GRI is being 
transmitted, 
block 

A wooden or metal case enclosing one or more pulleys and 
having a hook, eye, or strop by which it may be attached. 

bluff 

A headland or stretch of cliff having a broad nearly 
perpendicular face. See also cliff. 




B 


boat 

A fairly indefinite term. A waterborne vehicle smaller than 
a ship. One definition is a small craft carried aboard a ship. 
Submarines, however, are universally referred to as boats. 

boathook 

A hook or spike at the end of a pole. 

bobbing a light 

Quickly lowering the height of eye several feet and then 
raising it again when a navigational light is first sighted to 
determine whether or not the observer is at the geographic 
range of the light. If he is, the light disappears when the eye 
is lowered and reappears when it is restored to its original 
position, 
bollard 

A heavy post set into the edge of a wharf or pier to which 
the lines of a ship may be made fast. 

bolt holes 

Safe places to anchor or moor in the event that the weather 
worsens or mechanical difficulties occur. 

bolt rope 

Line attached to the foot and luff of a sail to give it strength 
or to substitute for sail slides. 

boom 

A spar attached to the mast for extending the foot of the sail. 

boom crotch or crutch 

A notched board or X-shaped frame that supports the main 
boom and keeps it from swinging when the sail is not 
raised. 

boomkin 

A short spar or structure projecting from the stem of a 
vessel to which the mizzen sail is sheeted. 

boom vang 

A tackle running from the boom to the deck which flattens 
the curve of the sail by pulling downward on the boom. 

boot top 

A painted line that indicates the designed waterline. 

boulder 

A detached water-rounded stone more than 256 millime¬ 
ters in diameter, i.e., roughly larger than a basketball. See 
also cobble. 


8 




B 


bow 

The forward part of a boat. 

bow line 

A docking line leading from the bow. 

bow spring line 

A line lead aft from the bow to the pier. 

bowline 


A knot used to form a temporary eye in the end of a line. 

bowsprit 

A spar extending forward from the bow. 

breakwater 

Anything which breaks the force of the sea at a particular 
place, thus forming protection for vessels. Often an artifi¬ 
cial embankment built to protect the entrance to a harbor, 
or to form an artificial harbor. See also jetty. 

bridge 

The location from which a vessel is steered and is con¬ 
trolled. Also, a structure erected over a depression or an 
obstacle such as a body of water, railroad, etc. to provide a 
roadway for vehicles or pedestrians. 

bridle 

A line or wire secured at both ends in order to distribute a 
strain between two points. 

brightwork 

Varnished woodwork andbbr polished metal. 

broach 


The turning of a boat 
parallel to the waves, 
subjecting it to possible 
capsizing. 

broad on the beam 

At right angles to the keel or centerline. Abeam (noF 
aboard the vessel). 

broad on the bow 

A direction midway between abeam and dead ahead. 

broad on the quarter 

A direction midway between abeam and dead astern. 

broad reach 

Sailing with the apparent wind coming over either quarter. 



9 




B - 

broadcast notice to mariners 

A radio broadcast designed to provide important marine 
information. 

building or house 

One of these terms, as appropriate, is used on nautical 
charts when the entire structure is a landmaiic, rather than 
an individual feature of it. 

bulkhead 

A transverse, vertical partition separating compartments. 

bulwark 

The side of a vessel when carried above the level of the 
main deck. 

buoy 

A floating object of defined shape and color, which is 
anchored at a given position and serves as an aid to 
navigation, 
buoy system 

IALA Maritime Buoyage System B applies to buoys and 
beacons that indicate the lateral limits of navigable chan¬ 
nels, obstructions, dangers such as wrecks, and other areas 
or features of importance to the mariner. 

burdened vessel 

That vessel which, according to the applicable Navigation 
Rules, must give way to another (privileged) vessel. The 
terms have been superseded by the terms “give-way” and 
“stand-on.” 

burgee 

A small yachting flag which is either swallow- tailed or 
pointed. 

by the lee 

Sailing with the wind on the same side as the boom; not a 
recommended point of sailing as it could cause an acciden¬ 
tal jibe. 

by the wind 

Sailing close hauled, beating. 

C 

cabin 

A living compartment aboard a vessel. 


10 




cable area 

Area shown on charts transited by submarine cables. 
Formal anchorage restrictions may apply in cable areas. 

cairn 

A mound of rough stones or concrete, particularly one 
serving or intended to serve as a landmark. The stones are 
customarily piled in a pyramidal or beehive shape. 

cape 

A relatively extensive land area jutting seaward from a 
continent, or large island, which prominently marks a 
change in or interrupts notably the coastal trend, 
capsize 

To turn over, 
carvel 

Smooth planked hull construction (see LAPSTRAKE). 

cast off 

To release mooring lines, 
catamaran ^ 

A twin-hulled boat, with hulls |J 
side by side. 

catboat 

A sailboat with a single sail attached to a mast stepped well 
forward. 

caulk 

To stop up and make watertight by filling with a waterproof 
compound or material. 

cavitation 

The rapid building and subsequent explosion of bubbles 
caused by and interfering with the action of the propeller. 
Destroys lift, and can actually damage the metal of the 
propeller and supports. 

centerboard 

A plate, in a vertical fore-and-aft plane, 
that is pivoted at the lower forward end, < 
and can be lowered or raised through a slot 
in the bottom of the boat to reduce leeway; 
movable keel used by sailboats, 
center of effort 

The center of wind pressure on a sail. 




11 







c - 

center of lateral resistance 

The center of underwater resistance which is approxi¬ 
mately the center of the boat’s underwater profile. 

chafing gear 

Tubing or cloth wrapping used to protect a line from wear 
on a rough surface. 

chain plate 

Metal strap fastened to the side of a boat, to which a stay or 
shroud is attached. 

channel 

1. That part of a body of water deep enough for navigation 
through an area otherwise not suitable. It is usually marked 
by a single or double line of buoys and sometimes by 
ranges. 2. The deepest part of a stream, bay, or strait, 
through which the main current flows. 3. A name given to 
a large strait, for example, the English Channel, 
characteristic 

The audible, visual, or electronic signal displayed by an aid 
to navigation to assist in the identification of an aid to 
navigation. Characteristic refers to lights, sound signals, 
racons, radiobeacons, and daybeacons. 

chart 

A nautical map for use by mariners or aviators, which 
depicts features and displays information of interest to 
these groups. 

Chart NO. 1 

A booklet prepared by the National Ocean Survey which 
contains symbols and abbreviations that have been ap¬ 
proved for use on nautical charts published by the U. S. 
Government. Past editions of this chart were in actual chart 
form. 

chart scale 

The number of distance units on the earth’s surface repre¬ 
sented by the same distant unit on the chart. Charts are 
typically partitioned on the basis of scale. Sailing charts 
have scales of 1:600,000 and greater. General charts have 
scales between 1:150,000 and 1:600,000. Coast charts 
have scales between 1:40,000 and 1:150,000. Harbor charts 
have scales larger than 1:40,000. 


12 




-c 

chart symbol 

A character, letter, or similar graphic representation used 
on a chart to indicate some object, characteristic, etc. May 
be called map symbol when applied to any map. 

chimney 

A relatively small, upright structure projecting above a 
building for the conveyance of smoke. 

chine 

The junction of the bottom and sides of a flat or v-bottomed 
boat. 

chock 

A fitting through which anchor or mooring lines are led. 

May be open or closed, 
clay (See mud.) 

clear 

To leave or pass safely, as to clear port or clear a shoal. 

clearing bearing 

British term for danger bearing. 

cleat 

A fitting to which lines are made fast. The 
classic cleat to which lines are belayed is 
approximately anvil-shaped, 
clew 

The after, lower comer of a sail to which is attached the 
sheets. 

cliff 

Land arising abruptly for a considerable distance above the 
water or surrounding land. See also bluff, 
close aboard 

Not on, but near to, a vessel. 

close-hauled 

Sailing with the boom hauled as close to the centerline of 
the vessel as is possible, thus sailing as much into the wind 
as is possible. Also known as beating, or “by the wind”; one 
of the three points of sailing, 
close reach 

Sailing with the sheets slightly eased and the apparent wind 
forward of the beam; between close-hauled and a beam 
reach. 


13 




c - 

closest point of approach 

The closest distance that a target will pass clear of the 
reference vessel. This distance is estimated from the rela¬ 
tive motion plot. The estimated time that this occurs is 
called the time to closest point of approach (TCPA), 
clove hitch ^ ^ 

A hitch temporarily fastening a line to a spar, I 

piling, or another line. 
clutter (radar) 

Unwanted radar echoes reflected from heavy i # 1 
rain, snow, waves, etc., which may obscure 1 
relatvely large areas on the PPI—and thus targets of 
interest. Related terms: sea clutter, sea return, rain clutter. 

coaming 

A vertical piece around the edge of a cockpit, hatch, etc. to 
prevent water on deck from running below, 
coastal confluence zone 

A zone extending seaward 50 nautical miles from shore or 
to the 100 fathom curve, whichever is greater. 

coastal navigation 

Navigation in coastal (sometimes called pilot) waters, 
where the opportunity exists to determine or check the 
vessel’s position by reference to navigational aids and 
observations (by either visual or electronic means) of the 
coast and its features, 
cobble (See stone) 
cocked hat 

Error triangle formed by lines of position that do not cross 
at a common point. So named because of the characteristic 
appearance of these lines in the vicinity of the fix. The size 
of the cocked hat is an indication of the precision of the 
fix—and is valuable information to the navigator. For this 
reason, conservative navigators term a position a fix only 
if at least three objects are used to determine the fix. Fixes 
determined only from two LOPs would be relegated to the 
status of estimated position in this view, 
cockpit 

An opening in the deck from which the boat is handled. 

coil 

To lay a line down in circular turns. 




coil down 

To coil a line. 

collar 

The reinforced opening in the deck or cabin roof through 
which the mast passes. This opening is constructed to take 
the strain of the mast. 

COLREGS, 72 

The International Regulations for Preventing Collisions at 
Sea, 1972, commonly called the International Rules. 

coming about 

The changing of course when close-hauled by swinging the 
bow through the eye of the wind and changing from one 
tack to another; reverse course or nearly so. 

commissioned 

Specialized term of art to denote the action of placing a 
previously discontinued aid to navigation back in opera¬ 
tion. 

compass card 

Part of a compass, the card is graduated in degrees, to 
conform with the magnetic meridian-referenced direction 
system inscribed with direction which remains constant; 
the vessel turns, not the card. 

compass errors 

Generic term used to describe all compass errors including 
variation, deviation, northerly turning error, acceleration 
error, heeling error. 

compass heading 

The direction a vessel is heading at any one instant as 
shown by its compass. 

compass point 

One of 32 points of the compass equal to 11-1/4 degrees. 

compass rose 

The resulting figure when the complete „ 

360° directional system is devel- 
oped as a circle with each degree // 
graduated upon it, and with the h 
000° indicated as true north. Also 
called true rose. This is printed on 
nautical charts for determining di 
rection. 

True Rom or Cocnpua Rom. 



15 






c - 

composite group-flashing light 

A group-flashing light in which the flashes are combined 
in successive groups of different numbers of flashes, 
composite group-occulting light 

A light similar to a group-occulting light except that the 
successive groups in a period have different numbers of 
eclipses. 

conformal projection 

A map or chart projection which preserves correct angular 
relationships. 

contact 

Any echo detected on the radarscope not evaluated as 
clutter or as a false echo. The term “contact” is used in a 
general sense, whereas “target” (q.v.) is used in a more 
particular sense to denote a contact about which more 
information (such as CPA, TCPA, course, or speed) is 
desired. Thus, radar targets would typically be plotted. Of 
course, the difference is not clear cut—one navigator’s 
contact might be another’s target, 
contour lines 

Lines that connect equal depth on a nautical chart, 
conventional direction of buoyage 

The general direction taken by the mariner when approach¬ 
ing a harbor, river, estuary, or other waterway from sea¬ 
ward, or proceeding upstream or in the direction of the 
main stream of flood tide, or in the direction indicated in 
appropriate nautical documents (normally, following a 
clockwise direction around land masses), 
coriolis force 

The deflective effect of the earth’s rotation on an object in 
motion which causes it to divert to the right in the northern 
hemisphere. (See rotary current.) 

correcting 

Converting a compass heading or a magnetic heading to its 
equivalent true heading, 
course (C) 

Course is the average heading and the horizontal direction 
in which a vessel is intended to be steered, expressed as the 
angular distance relative to north, usually from 000’ at 
north, clock- wise through359‘ from the point of departure 


16 




or start of the course to the point of arrival or other point of 
intended location, 
course deviation indicator 

An indicator, shown on some lorans, that graphically 
displays whether or not the vessel is on course and, if not, 
the direction to return to course. 

Course LOP 

An LOP situated approximately directly ahead or behind 
the vessel, so named because the LOP provides a good 
indication of the vessel’s CMG. 

Course Made Good (CMG) 

This indicates the single resultant direction from a point of 
departure to a point of arrival at a given time. (Synonym: 
Track Made Good) 

Course of Advance (COA) 

This indicates the direction of the intended path to be made 
good over the ground. 

Course Over Ground (COG) 

This indicates the direction of the path actually followed by 
the vessel over the ground , usually an irregular line, 
cove 

A small sheltered recess or indentation in a shore or coast, 
generally inside a large embayment. 

CQR plow 

An efficient anchor of British design, is clumsy to handle 
and stow. 

cradle 

A framework, generally of wood, to support a 
boat when it is out of the water. 

cringle 

A metal or plastic ring sewn into a sail 
through which a line may be passed to 
fasten the comer of the sail, 
cross rate (cross chain) 
interference 

Interference in the reception of radio signals from one loran 
chain caused by signals from another loran chain. 

cross track error 

Distance between the vessel’s actual position and the direct 
course between two waypoints. 







C - 

cross track error alarm 

Alarm that can be set on m any loran-C receivers that warns 
the navigator if the vessel’s cross track error exceeds some 
pre-specified value. 

crossing angle 

Generally, the angle between two LOPs which determine 
a fix. The closer the angle is to 90 degrees, the better the fix. 
Also used with loran LOPs. 

cruiser 

Somewhat more seaworthy craft that usually affords some 
sort of living quarters. 

cuddy 

A small shelter cabin in a boat, 
cumulus clouds 

Clouds with vertical development. 

Cunningham 

A grommeted hole in the mainsail luff slightly above the 
foot through which a line or hook is pulled downward to 
exert stress on the luff, thereby flattening the sail. 

cupola 

A small dome-shaped tower or turret rising from a build¬ 
ing. 

current 

Term used in two senses. It is used to refer either to the 
horizontal motion over the ground, including ocean cur¬ 
rent, tidal, and river currents, or more generally to these 
factors together with the effect of the wind and seas, 
steering error of the helmsman, compass error, speed curve 
error, and other factors, 
current (alternate definition) 

Generally, a horizontal movement of water. Currents may 
be classified as tidal and nontidal. Tidal currents are caused 
by gravitational interactions between the Sun, Moon, and 
the Earth and are a part of the same general movement of 
the seas that is manifested in the vertical rise and fall, called 
tide. Nontidal currents include the permanent currents in 
the general circulatory system of the sea as well as tempo¬ 
rary currents arising from more pronounced meteorologi¬ 
cal variability. 


18 




current correction angle 

The difference between the intended track and the calcu¬ 
lated course to steer to compensate for the estimated 
current. 

current difference 

Difference between the time of slack water (or minimum 
current) or strength of current in any locality and the time 
of the corresponding phase of the tidal current at a reference 
station, for which predictions are given in the Tidal Cur¬ 
rent Tables. 
current drift angle 

The difference in angle between the course steered and the 
resulting CMG in the presence of current. 

current ellipse 

A graphic representation of a rotary current in which the 
velocity of the current at different hours of the tidal cycle 
is represented by radius vectors and vectorial angles. The 
cycle is completed in one-half tidal day or in a whole tidal 
day according to whether the tidal current is of the semidi¬ 
urnal or the diurnal type. A current of the mixed type will 
give a curve of two unequal loops each tidal day. 
current sailing 

The process of allowing for current in determining the 
predicted course made good, or in determining the effect of 
a current on the direction and speed of motion of a boat. 

cutter 

A single masted sailboat with the mast stepped further aft 
than that of a sloop; an all- encompassing term used to 
describe Coast Guard vessels 65' and above. 



A plate, in a vertical fore-and-aft 
plane which can be lowered and raised 
vertically through a slot in the bottom 
of a boat to reduce leeway. 


dams 

Complex structures; allow water to flow to downstream 
pools in a controlled flow. 







Danforth anchor 

A patented lightweight anchor characterized i \ 
by long narrow twin flukes pivoted at one j j \ DAMF0RTt 
end of the relatively long shank. I 

danger bearing 

The maximum or minimum bearing of a^^£^ 
point for safe pasage of an off-lying danger. As a vessel 
proceeds along a coast, the bearing of a fixed point on 
shore, such as a lighthouse, is measured frequently. As long 
as the bearing does not exceed the limit of the predeter¬ 
mined danger bearing, the vessel is on a safe course with 
respect to the hazard in question, 
danger buoy 

A buoy marking an isolated danger to navigation, such as 
a rock, shoal or sunken wreck. 

datum 

The technical term for the base line from which a chart’s 
vertical measurements are made—heights of land or 
landmarks, or depths of water, 
davits 

Mechanical arms extending over the side or stem of a 
vessel, or over a sea wall, to raise or lower a smaller boat. 

daybeacon 

A fixed NAVAID structure used in shallow waters upon 
which is placed one or more Daymarks. 

daylight saving time 

A time used during the summer in some localities in which 
clocks are advanced one hour from the usual standard time. 

daymark 

A signboard attached to a daybeacon to convey naviga¬ 
tional information presenting one of several standard shapes 
(square, triangle, rectangle) and colors (red, green, orange, 
yellow, or black). Daymarks usually have reflective mate¬ 
rial indicating the shape, but may also be lighted, 
dead ahead 

A relative bearing of 000 degrees, 
dead astern 
Directly aft. 
dead in the water 

Adrift, floating with the current. 






dead reckoning 

The practice of estimating position by advancing a known 
position for courses and distance run.The effects of wind 
and current are not considered in determining a position by 
dead reckoning. 

dead reckoning plot 

A DR plot is the charted movement of a vessel as deter¬ 
mined by dead reckoning, 
dead reckoning (DR) position 

A position determined by dead reckoning, 
deck 

A permanent covering over a compartment, hull or any part 
thereof. 

demarcation line 

Boundary shown on nautical charts between areas where 
inland navigation rules and international regulation rules 
apply. 

departure 

A known location (fix) from which a dead reckoning plot 
is initiated. 

depth sounder 

An electronic means of measuring water depth by sound 
waves. 

deviation 

The effect of the vessel’s magnetic fields upon a compass. 
Deviation is the difference between the direction that the 
compass actually points and the direction that the compass 
would point if there were no magnetic fields aboard the 
vessel, 
diaphone 

A sound signal which produces sound by means of a slotted 
piston moved back and forth by compressd air. A “two- 
tone” diaphone produces two sequential tones with the 
second tone of lower pitch. 

dinghy 

A small open boat. A dinghy is often used as a tender for 
a larger craft. 

direction (true) 

The angle between the local true meridian and a line from 
the observer’s position to an object or another location. 




D - 

direction of relative motion 

Determined from the relative motion plot, this is the 
apparent course of the target as inferred from observations 
on the radar screen. 

directional light 

A light illuminating a sector or very narrow angle and 
intended to mark a direction to be followed. 

discontinued 

To remove from operation (permanently or temporarily) a 
previously authorized aid to navigation, 
discrepancy 

Failure of an aid to navigation to maintain a position or 
function as prescribed in the Light List. 

discrepancy buoy 

An easily transportable buoy used to temporarily replace an 
aid to navigation that is not watching properly. 

displacement 

The weight of water displaced by a floating vessel, thus, a 
boat’s weight. 

displacement hull 

A type of hull that plows through the water, displacing a 
weight of water equal to its own weight, even when more 
power is added, 
distress signal 

MAYDAY, MAYDAY, MAYDAY. 

diurnal 

Having a period or cycle of approximately one tidal day. 
Thus the tide is said to be diurnal when only one high water 
and one low water occur during a tidal day, and the tidal 
current is said to be diurnal when there is a single flood and 
single ebb period in the tidal day. A rotary current is diurnal 
if it changes its direction through all points of the compass 
once each tidal day. 
diurnal inequality 

The difference in height of the two high waters or of the two 
low waters of each day; also the difference in speed 
between the two flood tidal currents or the two ebb tidal 
currents of each day. The difference changes with the 
declination of the Moon and to a lesser extent with the 
declination of the Sun. 


22 




dividers 

An instrument consisting of two pointed legs joined by a 
pivot, and used principally for measuring distances or 
coordinates. An instrument having one pointed leg and the 
other carrying a pen or pencil is called a drafting compass. 

dock 

A protected water area in which vessels are moored. The 
term is often used to denote a pier or a wharf. 

documentation 

A special federal license or registration for a vessel. A 
vessel of 5 or more net tons, owned by a United States 
citizen,may be documented as a yacht. The process is 
administered by the U. S. Coast Guard. 

dolphin 

A minor aid to navigation structure consisting of a number 
of piles driven into the seabed or riverbed in a circular 
pattern and drawn together with wire rope. 

dome 

A large, rounded, hemispherical structure rising above a 
building or a roof of the same shape. 

double ebb 

An ebb tidal current where, after ebb begins, the speed 
increases to a maximum called first ebb\ it then decreases, 
reaching a minimum ebb near the middle of the ebb period 
(and at some places it may actually run in a flood direction 
for a short period); it then again ebbs to a maximum speed 
called second ebb after which it decreases to slack water, 
double flood 

A flood tidal current where, after flood begins, the speed 
increases to a maximum called firstflood\ it then decreases, 
reaching a minimum flood near the middle of the flood 
period (and at some places it may actually run in an ebb 
direction for a short period); it then again floods to a 
maximum speed called second flood after which it de¬ 
creases to slack water, 
double sheet bend 

A secure knot used to tie together two lines of unequal 
diameter. 




D 


double tide 

A double-headed tide; that is, a high water consisting of 
two maxima of nearly the same height separated by a 
relatively small depression, or a low water consisting of 
two minima separated by a relatively small elevation. 
Sometimes, it is called an agger. 
doubling the angle on the bow 

A method of calculating a running fix by measuring the 
distance a vessel travels on a steady course while the 
relative bearing (right or left) of a fixed object doubles. The 
distance from the object at the time of the second bearing 
is equal to the distance run between bearings, neglecting 
drift, 
douse 

To lower sails quickly. 

downhaul 

A line attached to the boom at the tack area of the sail in 
order to pull the luff of the sail downward. 

draft 

The vertical depth from the bottom of the keel to the top 
of the water. 

drift 

The speed in knots at which the current is moving. Drift 
may also be indicated in statue miles per hour in some 
areas, the Great Lakes, for example. The term is also 
commonly used to mean the speed at which a vessel 
deviates from the course steered due to the combined 
effects of external forces such as wind and current 
Drnis 

A term used to describe the statistical accuracy of a loran 
or other fix. Twice the Dims is a radius of a circle that 
should include the fix point with at least 95 % certainty. The 
geodetic accuracy limit of the loran-C system within the 
designated coverage area is that 2Drms should be less than 
0.25 nautical miles, 
drogue 

Any device streamed astern to slow a vessel’s speed, or to 
keep its stem to the waves in a following sea. 


24 




drying heights 

Heights above chart sounding datum of those features 
which are periodically covered and exposed by the rise and 
fall of the tide. 

dual rate blanking 

To provide continuous service from one loran-C chain to 
the next, some stations are dual rated (see dual rated). A 
dual rated station is faced periodically with an impossible 
requirement to radiate two overlapping pulse groups at the 
same time. During the time of overlap, the subordinate 
(secondary) is blanked or suppressed, 
dual rate station 

Term used to describe a master or secondary station in one 
loran-C chain that is also used as a master or secondary in 
another chain. The Dana, Indiana, loran transmitter is one 
example, serving as the zulu secondary in the 9960 (North¬ 
east U.S.) chain as well as the master in the 8970 (Great 
Lakes) chain, 
dumping ground 

Area shown on charts where dumping took place (the 
practice is no longer permitted) and which may present a hazard 
to navigation. 

duration of flood and duration of ebb 

Duration of flood is the interval of time in which a tidal 
current is flooding, and the duration of ebb is the interval 
in which it is ebbing, 
duration of rise and duration of fall 

Duration of rise is the interval from low water to high 
water, and the duration of fall is the interval from high 
water to low water. 

Dutchman’s log 

A buoyant object thrown overboard to determine the speed 
of the vessel. The time required for a known length of the 
vessel to pass the object (assumed to be dead in the water) 
is measured. Speed can be computed from the two known 
values of time and distance. The Dutchman’s log can also 
be used to measure the drift of the current if a vessel can be 
held stationary (keep station) with respect to a fixed object. 




E 


E 


ease off 

To slacken or relieve tension on a line. 

ebb current 

The movement of a tidal current away from shore or down 
a tidal river or estuary. In the mixed type of reversing tidal 
current, the terms greater ebb and lesser ebb are applied 
respectively to the ebb tidal currents of greater and lesser 
speed of each day. The terms maximum ebb and minimum 
ebb are applied to the maximum and minimum speeds of a 
current running continuously ebb, the speed alternately 
increasing and decreasing without coming to a slack or 
reversing, 
ebb tide 

A receding tide, 
echo 

Term used in radar to denote an object that reflects the radar 
beam, often used interchangeably with the terms return, 
target, blip, contact and pip. Properly speaking, however, 
there are subtle distinctions among these. See, for example, 
contact, 
eclipse 

An interval of darkness between appearances of a light. 

electronic bearing line 

An adjustible bearing line which appears as a spoke radi¬ 
ating from the center of the PPI. EBLs are used to measure 
the bearing of a target. Also called electronic bearing 
marker. 

electronic bearing marker 

See electronic bearing line. 

electronic chart 

A device that can display a chartlike representation on a 
screen. Some electronic charts are very elaborate and allow 
the user to “zoom in” to examine an area at a larger scale. 
Depth contours, NA V AIDS, and other chart features can be 
displayed—even down to individual docks at certain loca¬ 
tions. Electronic charts can interface with other shipboard 
electronics, such as a loran and display the vessel’s current 
position, waypoints, and related information. 


26 




- E 

emergency light 

A light of reduced intensity displayed by certain aids to 
navigation when the main light is extinguished. 

Emergency Position Indicating Radio Beacon(EPlRB) 

A device which emits a continuous radio signal alerting 
authorities to the existence of a distress situation and 
leading rescuers to the scene, 
endurance 

The time in hours that the vessel can be operated at a given 
throttle setting until the enroute fuel is exhausted. 

enroute fuel 

Fuel intended for use in a voyage. Numerically the enroute 
fuel is the fuel on board minus an allowance for a fuel 
reserve. Also termed voyage fuel. 

ensign 

A national or organizational flag flown 
aboard a vessel. 

equator 

Great circle formed by passing a plane 
perpendicular to the axis of rotation of the 
equatorial tidal currents 

Tidal currents occuring semimonthly as the result of the 
Moon being over the Equator. At these times the tendency 
of the Moon to produce a diurnal inequality in the tide is at 
a minimum, 
equitorial tides 

Tides occuring semimonthly as the result of the moon 
being over the equator. At these times the tendency of the 
moon to produce a diurnal inequality in the tide is at a 
minimum. 

establish 

To place an authorized aid to navigation in operation for the 
first time. 

estimated position (EP) 

An improved position based upon the DR position and 
which may include, among other things, factoring in the 
effect of wind and current, a single line of position, or all 
of the above. 


USCGAUX 

ENSIGN 

earth. 


27 




E - 

even keel 

When a boat is floating on its designed waterline, it is said 
to be floating on an even keel; not listing to port or 
starboard, upright. 

existence doubtful 

Term used principally on charts to indicate the possible 
existence of a rock, shoal, or other obstruction, for which 
the actual existence has not been established. 

extinguished 

A lighted aid to navigation which fails to show a light 
characteristic. 

eye bolt 

A bolt having a looped head designed to receive a davit 
hook or towing line. This bolt is usually bolted through the 
deck or stem and/or the transom when present. 

eye of the wind 

The direction from which the wind is blowing, 
eye splice 

A permanent loop spliced in the end of a line. 

F 



fair current 

Current moving in the same diretion as the vessel. 

fairlead 

A fitting used to change the direction of a line, 
faking down 

Laying the line in coils. 

fall off 

To turn the bow of the boat away from the direction of the 
oncoming wind, 
fast 

Said of an object that is secured to another. 

fathom 

A nautical measure of length, six feet, used for measuring 
water depth and length of anchor rode. 

fender 

A cushion, placed between boats, or between a boat and a 
pier, to prevent damage. 



28 






F 


fiberglass 

Resin reinforced with fibrous glass (or glass reinforced 
plastic) used in boat construction. Its forms are mat, cloth, 
woven roving, and chopped strands. 

fid 

A tapered, pointed tool used to separate strands of rope 


when splicing. 

figure-eight knot 

A knot in the form of a figure eight usually tied at the end 
of a line as a stopper to keep the end of the line from passing 
through a block or fairlead. 

fin keel 

A thin narrow keel bolted to the bottom of a vessel’s hull. 

fire extinguisher 

A device for extinguishing fires. Classified by size 
and type of fire for which it is designed. 

fisherman’s anchor 

A small mushroom anchor sometimes used in pro¬ 
tected waters to hold a boat in position briefly. 

fisherman’s bend 

A hitch for making fast to a mooring buoy or spar or to the 
ring of an anchor. 

fix 


A known position determined by passing close aboard an 
object of known position or determined by the intersection 
of two or more lines of position (LOPs) adjusted to a 
common time, determined from terrestrial, electronic, and/ 
or celestial data. The accuracy, or quality of a fix, is of great 
importance, especially in coastal waters, and is dependent 
on a number of factors, 
fixed ATON 

An aid to navigation placed on a fixed structure such as a 
light house, tower, etc. 

fixed bridge 

A bridge that does not lift, swing, or otherwise open for 
vessel traffic. 

fixed light 

A light showing continuously and steadily, as opposed to 
a rhythmic light. (Do not confuse with “fixed” as used to 
differentiate from “floating.”) 


29 





F 


fixed range markers 

A series of concentric range rings displayed on a PPL The 
spacing of these rings can be adjusted by a range switch, but 
all FRMs are fixed in relation to each other, 
flag tower 

A scaffold-like tower from which flags are displayed. 

flagpole 

A single staff from which flags are displayed. The term is 
used when the pole is not attached to a building. 

flagstaff 

A flagpole rising from a building. 

flame arrester 

A safety device on an inboard or inboard-outboard engine, 
usually made of metal mesh, which prevents an explosion 
from an exhaust backfire. 

flare 

The outward curve of a vessel’s sides near the bow. A 
pyrotechnic distress signal. 

flash 

A relatively brief appearance of a light, in comparison with 
the longer interval of darkness in the same character. 

flash tube 

An electronically controlled high-intensity discharge lamp 
with a very brief flash duration. 

flashing light 

A light in which the total duration of light in each period is 
clearly shorter than the total duration of darkness and in 
which the flashes of light are all of equal duration. (Com¬ 
monly used for a single-flashing light which exhibits only 
single flashes which are repeated at regular intervals.) 
flemish 

A decorative method of coiling a line flat 
on the deck or dock. 

float plan 

A document that describes the route(s) and estimated time 
of arrival of a particular voyage. The float plan generally 
includes a description of the vessel, radio and safety 
equipment carried, planned stops, names of passengers, 
and other pertinent information. 



30 




floating aid to navigation 

A buoy, secured in its assigned position by a mooring. 

flood current 

The movement of a tidal current toward a shore or up a tidal 
river or estuary. In the mixed type of reversing current, the 
terms greater flood and lesser flood are applied respec¬ 
tively to the flood currents of greater and lesser speed of 
each day. The terms maximum flood and minimumflood are 
applied to the maximum and minimum speeds of a flood 
current, the speed of which alternately increases and de¬ 
creases without coming to a slack or reversing, 
flood tide 
A rising tide, 
floorboards 

The surface of the cockpit on which the crew stand. 

fluke 

The flat palm-shaped or shovel-shaped part of an anchor 
which digs in to prevent dragging. 

fluxgate compass 

A compass that senses the earth’s magnetic field electroni¬ 
cally, rather than with magnets. Fluxgate compasses can 
interface with other shipboard electronics such as radar or 
loran. 

fly 

A pennant at the masthead. 

flying bridge 

An added set of controls above the level of the normal 
control station for better visibility. Usually open but may 
have a collapsible top for shade, 
fog 

Goud that forms at or near the earth’s surface. 

fog detector 

An electronic device used to automatically determine 
conditions of visibility which warrant the turning on and 
off of a sound signal or additional light signals. 

fog signal 

See Sound Signal, 
following sea 

Sea in which the waves move in a direction approximately 
the same as the vessel’s heading. Opposite of head sea. 




F - 

foot 

The lower edge of a sail, 
fore-and-aft 

In a line parallel to the keel, 
forepeak 

A compartment in the bow of a vessel, 
foresail 

The lower sail set abaft the foremast of a schooner. 

forward 

Toward the bow of the boat, 
foul current 

Current moving in the opposite direction to the vessel. 

foul ground 

An area unsuitable for anchoring due to being strewn with 
rocks, boulders, coral, or obstructions. Foul grounds are 
often shown on nautical charts. 

fouled 

Any piece of equipment that is jammed or entangled, or 
dirty. 

founder 

When a vessel fills with water and sinks. 

four-stroke engine 

An engine whose working cycle involves four strokes of 
the piston: intake, compression, power, and exhaust. 

freeboard 

The minimum vertical distance from the 
surface of the water to the gunwale cap. 

frequency 

The rate at which a cycle is repeated. 

front 

The juncture or boundary between two air masses of 
different temperatures. 

fuel consumption chart 

Chart or graph that relates the engine throttle setting, speed 
through the water, and the fuel bum rate in gallons per hour. 

fuel efficiency 

The distance that a vessel can travel on each gallon of fuel. 
Fuel efficiency is a function of the throttle setting and 
several other factors. 



ABEAM 



32 









fuel reserve 

A quantity of fuel set aside for possible contingencies. 

full and by 

Close-hauled. 

furl 

To fold, gather, or roll up a sail on top of a boom or spar and 
secure it with small lines. 

G 


gaff 

A spar to support the head of a gaff sail. A hook-like 
device used to boat a large fish, 
galley 

The kitchen area of a boat. 

gangplank 

The temporary ramp or platform between the vessel and the 
wharf or pier, 
gangway 

The area of a ship’s side where people board and 
disembark, 
gasket 

A sail stop. 

gear 

A general term for ropes, blocks, tackle and other equip¬ 
ment. 

Geometric Dilution of Precision (GDOP) 

Term used to include all geometric factors (gradient, 
crossing angle) that degrade the accuracy of position fixes 
from externally referenced navigation systems, such as 
loran-C. GDOP can be calculated from an equation which 
summarizes these effects in one single number, 
gimbals 

A pair of rings pivoted on axes at right angles to each other 
so that one is free to swing within the other; a ship’s 
compass, etc., will keep a horizontal position when sus¬ 
pended on gimbals, 
give-way vessel 

A term, from the Navigational Rules, used to describe the 
vessel which must yield in meeting, crossing, or overtaking 
situations. 




G - 

gnomon rod 

A long narrow nail placed vertically through the center of 
the rose, will cast its shadow on the compass rose. 

gong 

A wave-actuated sound signal on buoys which uses a group 
of saucer-shaped bells to produce different tones, 
gooseneck 

A universal joint connecting the mast and the boom, 
allowing movement of the boom in any direction. 

GPS 

Global Positioning System, an electronic navigation sys¬ 
tem using satellites for world wide coverage. 

grab rails 

Hand-hold fittings mounted on cabin tops and sides for 
personal safety when moving around the boat. 

gradient 

The ratio of the spacing between adjacent loran TDs, as 
measured in nautical miles, yards, or feet, and the number 
of microseconds difference between these lines. Generally 
speaking, the smaller the gradient, the better the fix. 

grapnel 

A straight shank anchor with four or five curved claw-like 
arms and no stock; used mostly for recovering lost articles 
or objects. 

graticule 

The network of lines representing parallels and meridians 
on a map, chart, or plotting sheet, 
gravel 

See stone. 

great circle 

The circle formed on the earth’s surface when 
a plane is passed through the earth’s center. 

great diurnal range 

The difference in height between mean highei 
and mean lower low water. The expression may also be 
used in its contracted form, diurnal range. 

grommet 

A ring or rope of metal used to fasten the edge of a sail to 
its stay, hold an oar in place, etc. 



34 






ground swell 
See swells, 
ground tackle 

A collective term for the anchor and its associated gear. 

groundwave 

A radio wave that travels near or along the earth’s surface. 
Groundwave signals are used for the present loran system. 

group flashing light 

A navigational aid light which emits flashes in groups, 
specified in number, and repeated at regular intervals. 

group occulting light 

An occulting light in which a group of eclipses, specified 
in number, is regularly repeated, 
group repetition interval 

Length of time (in microseconds) between the start of one 
transmission from the master station in a loran-C chain and 
the start of the next. For convenience the GRI is usually 
divided by 10. Thus, for example, the 9960 GRI Northeast 
U. S. Chain has a group repitition interval of 99,600 
microseconds, 
gudgeon 

The eye supports for the rudder, mounted on the transom 
and designed to receive the pintles. 

gulf 

That part of an ocean or sea extending into the land, usually 
larger than a bay. 

Gulf Coast low water datum 

A chart datum. Specifically, the tidal datum formerly 
designated for the coastal waters of the Gulf Coast of the 
United States. It was defined as mean lower low water 
when the type of tide was mixed and mean low water *hen 
the type of tide was diurnal, 
gunwale 

The upper edge of a boat’s sides. 

H 

hachures 

Short marks on topographic maps or nautical charts to 
indicate the slope of the ground or the submarine bottom. 
These marks usually follow the direction of the slope. 




H 


half hitch 

The simplest kind of hitch; a knot made by passing the end 
of the rope around the rope and then through the loop just 
made. 

half-tide level 

See mean tide level. 

halyard 

A line or wire used to hoist a spar, sail, or flag. 

hand-bearing compass 

Portable compass (magnetic or electronic) that can be used 
aboard ship for taking bearings. 

hanks 

Snap hooks which attach the luff of a heklsail to the 
forestay; unit of measurement for small cotton line. 

hard alee 

The operation of putting the helm (tiller) to the lee side of 
a boat when coming about during a tacking maneuver. 

hard chine 

An abrupt intersection between the hull side and the bottom 
of a boat. 

hatch 

An opening in a boat’s deck fitted with a watertight cover. 

hawser 

A heavy rope or cable used for mooring or towing. 

head 

A marine toilet. Also the upper comer of a triangular sail. 

head sea 

Sea in which the waves move in a direction approximately 
opposite the vessel’s heading. Opposite of following sea. 

header 

A change in wind direction which will head or impede 
progress in an intended direction, 
heading (HDG) 

The instantaneous directioin of a vessel’s bow. It is ex¬ 
pressed as the angular distance relative to north, usually 
000° at north, clockwise through 359°. Heading should not 
be confused with course. Heading is a constantly changing 
value as a vessel yaws back and forth across the course due 
to the effects of sea, wind, and steering error. Heading is 


36 




expressed in degrees of either true, magnetic, or compass 
direction. 

heading flash 

An illuminated radial line on the PPI of a radarscope for 
indicating the reference ship’s heading on the bearing dial. 
Also called heading marker. 

heading up 

Swinging the bow of a sailing vessel closer to the eye of the 
wind. 

headsails 

Sails set forward of the foremost mast. 

headway 

The forward motion of a boat through the water. Opposite 
of stemway. 

heave to 

To bring a vessel up in a position where it will maintain 
little or no headway, usually with the bow into the wind or 
nearly so. To stop. 

heavy iron 

Slang expression used to denote large ships. 

heel 

To tip or lean to one side. 

helm 

The wheel or tiller controlling the rudder. 

helms person 

The person who steers the boat. (Helmsman is traditional 
name.) 

high frequency (HF) 

A special frequency band used in long-distance communi¬ 
cations. 

high water (HW) 

The maximun height reached by a rising tide. The height 
may be due solely to the periodic tidal forces or it may have 
superimposed upon it the effects of prevaling meteorologi¬ 
cal conditions. 

higher high water (HHW) 

The higher of the two high waters of any tidal day. 
higher low water (HLW) 

The higher of the two low waters of any tidal day. 




H - 

hiking out 

The position one assumes when positioned on 
the weather rail in an effort to balance the 
heeling forces of the wind upon thesailsand/or 
rigging. 

hiking stick 

A short stick attached to the tiller which allows 
the helmsperson to hike out while steering the boat. 

hitch 

A knot used to secure a rope to another object or to another 
rope. 

hold 

A compartment below deck in a large vessel, used solely 
for carrying cargo. 

hole 

A small bay (or channel), particularly in New England. 

homing 

Process of moving toward a location by continually point¬ 
ing the bow of the vessel in the direction of the station. In 
the absence of current, homing will lead to a ground track 
that is a straight line. With any current, the ground track 
will become curved, bowed in the direction of the prevail¬ 
ing current, 
hook 

Something resembling a hook in shape, particularly, a. a 
spit or narrow cape of sand or gravel which turns landward 
at the outer end; or b. a sharp bend or curve, as in a stream. 

horn 

A sound signal which uses electricity or compressed air to 
vibrate a disc diaphragm. 

horse 

The wire or rope bridle to which is attached the block 
through which the sheet(s) run. 

houseboat 

A popular modification of the cruiser, can offer all the 
conveniences of home. 

HOWGOZIT Chart 

Chart that depicts the vessel’s actual fuel quantity at 
various points in a voyage in comparison to the amount of 
fuel required to reach the destination with various levels of 
fuel reserves. 



38 








I 


hug 

To remain close to, as to hug the shore. 

hull 

The main body of a vessel, 
hull identification number (HIN) 

A number that includes the Manufacturers ID Code, Hull 
Serial number, Date of Certification, and model year, 
displayed on the boat hull, 
hull speed 

The maximum speed of a displacement vessel. It is limited 
by the length of the vessel and the shape of its underwater 
construction. 

humidity 

Moisture in the air. 

hurricane 

A large, tropical storm, measuring hundreds of miles in 
diameter with steady winds in excess of 65 knots. Called a 
typhoon in the Pacific Ocean. Inland it is a cyclone. 

hydraulic current 

A current in a channel caused by a difference in the surface 
levels at the two ends. Such a current may be expected in 
a strait connecting two bodies of water in which the tides 
differ in time or range. 

hygrometer 

An instrument to measure the humidity. 

hyperbolic grid 

Lattice of curved (hyperbolic) lines of position produced 
by a hyperbolic system. 

hyperbolic system 

Navigation system, such as loran-C, that operates by 
measuring the time difference between signals transmitted 
by two or more transmitters. 

I 

in irons 

Inability to maneuver without placing vessel in jeopardy. 
Stalled. Said of a sailboat headed into the eye of the wind, 
with no wind pressure on either side of the sails. 


39 




I 


inboard-outboard powered 

This arrangement places the engine against the transom. 
The power drive shaft then exits through a special fitting 
mounted on the transom. 

inboard-powered 

When the engine is mounted inside the hull. 

inclinometer 

Device to measure the angle of roll of a vessel. 

index diagram 

An inset in a nautical chart where contiguous or related 
charts at different scales are noted. 

induction system 

Fuel-air mixture is created by the carburetor and is piped to 
the intake valves through the intake manifold. 

initial stability 

A boat’s tendency to resist initial heel from the upright 
position. 

inoperative 

Sound signal or electronic aid to navigation out of service 
due to a malfunction. 

interrupted quick light 

A quick flashing light in which the rapid alternations are 
interrupted at regular intervals by eclipses of long duration. 
Intracoastal Waterway (ICW) 

A waterway running parallel to the Atlantic and Gulf 
Coasts from Manasquan Inlet on the New Jersey shore to 
the Mexican border, 
intrusion alarm 

Alarm that can be set on a radar to alert the radar operator 
that a target has penetrated a range ring. 

iron jenny 

Slang expression to denote the engine of a sailboat. 

isogonic lines 

Lines on a chart connecting points of equal magnetic 
variation. 

isolated danger mark 

A mark erected on, or moored above or very near, an 
isolated danger which has navigable water all around it. 


40 




-J 

isophase light 

A rhythmic light in which all durations of light and 
darkness are equal. (Formerly called equal interval light.) 

isthmus 

A narrow strip of land connecting two larger portions of 
land. 


J 


jet drive 

A special form of an inboard/outboard, since it has an 
inboard-mounted engine and uses directed thrust. 

jet ski 

A personal watercraft driven by a pump instead of a 
propeller. 

jetty 

A structure built out into the water to restrain or direct 
currents, usually to protect a river mouth or harbor entrance 
from silting, etc. 


A triangular sail set forward of the mainmast (sloop, cutter, 
ketch, yawl) or the foremast (schooner). 

jib sheet 

The line, usually paired, controlling the lateral movement 
of the jib. 

jib stay 

A stay running from the bow to the upper part of the mast 
on which the jib is attached. 

jibe 

The maneuver of changing the sail 
(and boom) from one side of the boat 
to the other. Usually used as a method ^ 
of changing course while keeping 
the wind astern. ^ " 

jumper 

A stay on the upper forward part of a mast. 


41 




J - 

jumper stays 

A wire line which runs over the end of a jumper strut to 
provide support for the upper portion of a mast above the 
forestay. 

jumper struts 

A short horizontal spar placed above the union of the 
forestay and the mast over which a jumper stay runs. 

junction 

The point where a channel divides when proceeding sea¬ 
ward. The place where a tributary departs from the main 
stream. 


K 


kedge 

To use an anchor to move a boat by hauling on the anchor 
rode. A small anchor used in light work, 
keel 

The main structural member of a vessel running fore-and- 



aft; the backbone of a vessel. 

keel boat 

A boat with a fixed keel as opposed to a boat with a 
centerboard or daggerboard. 

ketch 

A two-masted sailboat with the smaller 
after mast (mizzen) stepped ahead of the 
rudder post. 

“kicking” the stern _ 

A means of controlling a boat’s direction by forcing water 
from the propeller over the rudder before the boat has 
gained forward headway. 

knock down 

A boat laid over laterally by wind or sea, allowing water to 
come in over the gunwales, 
knot (kn sometimes kt) 

A measure of speed equal to one nautical mile (6076 feet) 
per hour. 

knot 


A fastening made by interweaving rope to form a stopper, 
to enclose or bind an object, to form a loop or a noose, to 
tie a small rope to an object, or to tie the ends of two small 
ropes together. 


42 








L 


ladder 

Stairs or steps aboard a vessel. 

landmark 

A conspicuous artificial feature on land, other than an 
established aid to navigation which can be used as an aid to 
navigation. Sometimes also used in a less technical sense 
to include natural features as well as artificial features. 

lapstrake 

Hull construction of overlapping planks; alsq known as 
clinker-built construction (see CARVEL), 
large navigational buoy (LNB) 

Buoys developed to replace lightships and are placed at 
points where it is impractical to build a lighthouse. The 
unmanned LNBs are 40 feet in diameter with light towers 
approximately 40 feet above the water. LNBs are equipped 
with lights, sound signals, radiobeacons, and racons. LNBs 
are painted red, not for lateral significance, but to improve 
visibility, 
lateen rig 

A sailing rig in which the sail is oriented fore-and-aft. A 
design which originated in theNear East and is still found 
there. Consists of a triangular (lateen) sail, one side of 
which is very short, slung from a lateen yard, a long, 
movable spar which crosses the relatively short mast at the 
midpoint of the yard and at an angle to the mast. The same 
rig is often used on sailboards, 
lateral resistance 

That resistance to the leeway or sideways movement of a 
boat caused by wind or wave forces determined by the 
amount of heel, keel or centerboard below the water line. 

lateral system 

A system of aids to navigation in which characteristics of 
buoys and beacons indicate the sides of the channel or route 
relative to a conventional direction of buoyage (usually 
upstream). 

latitude 

Distance north or south of the equator expressed in degrees 
from zero to ninety, north or south; i.e., L 073N. 




L - 

lay 

To “lay a marie” is to be able to reach it without tacking. The 
lay of a line is the direction in which its strands are twisted, 
usually to the right, 
lazarette 

A storage space in a boat’s stem area. 

lead line 

A line used to measure the depth of the water. 

leading lights 

British terminology for range lights, 
ledge 

On the sea floor, a rocky projection or outcrop, 
lee 

The side sheltered from the wind; the direction toward 
which the wind is blowing. 

lee helm 

The condition, in a sailing vessel, when the helm must be 
kept to leeward to hold a boat on her course. 

leeboard 

Pivoted board attached to the side of a sailboat to reduce 
leeway; usually one on either side, that to leeward being 
lowered when in use. 
leech 

The after edge of a fore-and-aft sail. 

leeward 

The direction away from the wind. Opposite of windward, 
leeway 

The sideways movement of the boat caused by either wind 
or current. 

left-handed propeller 

A propeller designed to rotate in a counter-clockwise 
direction when viewed from aft; often paired with a right- 
handed propeller on a twin-screw boat, 
leg 

That portion of a voyage track that can be represented by a 
single course line. A track could be composed of several 
legs. 

legend 

A title or explanation on a chart, diagram, illustration. 

lifeline 

Lines, usually plastic-covered wire rope, placed alongside 


44 




a boat’s deck to keep the crew and passengers from falling 
overboard. 

lift 

An increase in the wind’s force, causing an increase of heel 
of a boat close-hauled, shifting the center of effort forward, 
allowing the boat to sail, often advantageously, closer to 
the wind and faster. Sometimes said of a similarly advan¬ 
tageous shift in wind direction. Being lifted is the opposite 
of being headed, 
light 

Lighthouses or beacons, fixed aids to navigation, or a 
vessel’s navigation lights. On a vessel, lights are designed 
to help identify the size, direction of movement, status of 
the vessel, and sometimes the tasks being performed. 

Light List 

USCG Publication. 

light sector 

The arc over which a light is visible, described in degrees 
true, as observed from seaward towards the light. May be 
used to define distinctive color difference of two adjoining 
sectors, or an obscured sector. 

lighted ice buoy (LIB) 

A lighted buoy without sound signal, and designed to 
withstand the forces of shifting and flowing ice. Used to 
replace a conventional buoy when that aid to 
navigation is endangered by ice. 

lighthouse 

A lighted beacon of major importance. 

line 

Rope and cordage used aboard a vessel, 
line of position (LOP) 

A line of bearing to a known origin or reference, upon 
which a vessel is assumed to be located. An LOP is 
determined by observation (visual bearing) or measure¬ 
ment (RDF, loran, radar, etc.). An LOP is assumed to be a 
straight line for visual bearings, or an arc of a circle (radar 
range), or part of some other curve such as hyperbola 
(loran). LOPs resulting from visual observations (mag¬ 
netic bearings) are generally converted to true bearings 
prior to plotting on a chart. 





L - 

line of sight 

The straight line between two points. This line is in the 
direction of a great circle, but does not follow the curvature 
of the earth. 

Local Notice to Mariners 

A written document issued by each U. S. Coast Guard 
district to disseminate important information affecting aids 
to navigation, dredging, marine construction, special ma¬ 
rine activities, and bridge construction on the waterways 
within that district, 
lockmaster 

A person responsible for lock operations, 
locks 

A means of passing vessels through a dam and, at the same 
time, raising or lowering them to the level of the next pool, 
log 

A daily record of a ship’s progress or operations and 
messages sent or received on its radio. A device to measure 
a vessel’s speed. To record a ship’s progress in a journal. 

longitude 

Distance east or west of the prime meridian expressed in 
degrees from zero to 180°east or west; i.e., Lo 123W. 

long splice 

A method of joining two ropes without increasing the 
diameter of the rope. Normally used when line must pass 
thru a block or over a fairlead without jamming, 
lookout station(watchtower) 

A tower atop a small house used for observation, 
loose-footed 

A sail secured to the boom only at the tack and the clew,as 
opposed to a sail secured with slides. 

loran 

A contraction of long-range navigation, used to describe an 
electronic navigation system using a chain of transmitting 
stations that allows mariners (or aviators) to determine 
their position. 

loran-C LOP 

Line of position as determined from reception of the loran 
master signal and that of one secondary. Loran-C LOPs at 
convenient intervals are plotted on NOAA charts. See also 
rate. 


46 




loran chain 

Series of three to five transmitting stations consisting of a 
master station and two to four secondary stations used in 
the loran system, 
loran linear interpolator 

A small inset diagram shown on loran overprinted charts 
that enables interpolation of time differences, 
loran pulse 

Basic “building block” of the transmitted loran signal. The 
loran pulse exhibits a characteristic (and well controlled) 
waveform which can be identified and timed by a receiver. 
The loran signal from a master station actually consists of 
nine pulses. The first eight pulses are spaced 1,000 micro¬ 
seconds apart, followed at an interval of 2,000 microsec¬ 
onds by the ninth pulse. Secondary stations transmit only 
eight pulses, each separated by 1,000 microseconds. Pulsed 
transmission saves on the power required for signal trans¬ 
mission and facilitates signal identification. Multiple pulse 
transmission is used rather than single pulse transmission 
to increase the average power of the loran signal, 
low water (LW) 

The minimum height reached by a falling tide. The height 
may be due solely to the periodic tidal forces or it may have 
superimposed upon it the effects of meteorological condi¬ 
tions. Use of the synonymous term, low tide , is discour¬ 
aged. 

lower high water (LHW) 

The lower of the two high waters of any tidal day. 
lower low water (LLW) 

The lower of the two low waters of any tidal day. 

lower shrouds 

The shrouds which run from the chain plates at the sides of 
the boat to the mast just beneath the intersection of the 
spreaders. 

loxodrome 

Any line on the earth’s surface (other than due cast or due 
west) which cuts successive meridians of longitude at the 
same oblique angle. When extended, it spirals toward, but 
never reaches, one of the earth’s poles. 


47 




lubber’s line 

A mark or permanent line on a compass which is 
used to read the compass heading of a vessel. 

When properly mounted it is parallel to the 
vessel’s keel. 

luff 

The forward edge of a sail; also the action of 
heading up into the wind causing the sail to flutter. 

luminous range diagram 

A diagram used to convert the nominal range of a light to 
its luminous range under existing conditions. The ranges 
obtained are approximate. 

lunar day 



The duration of one rotation of the earth on its axis, with 
respect to the moon. Its average length is about 24 hours 
and 50 minutes. 


M 

magnetic compass 

A magnet, balanced so that it can pivot 
freely in a horizontal plane; a sailor’s most 
common and most reliable direction-indicating aid. 

magnetic direction (M) 

A direction relative to the earth’s magnetic field and 
magnetic north. Magnetic courses are sometimes labeled 
with an “M,” to signify “magnetic.” 

magnetic meridian 

A system of “meridians” passing through the earth’s mag¬ 
netic poles. A compass aligns with these “meridians” if 
there is no local magnetic field on the vessel to cause 
deviation. 

mainmast 

The principal mast of a sailboat. 

mainsail 

The principal sail that is set on the mainmast, 
mainsheet 

The sheet controlling the athwartships movement of a 
mainsail. 







M 


maneuvering board 

A printed compass rose which is used together with parallel 
rulers and dividers to solve problems of the movement of 
vessels relative to each other such as those that arise when 
the vessels change position relative to each other. Used, for 
example, when another vessel is observed on a radar scope, 
marine engine 

An internal combustion engine, either gasoline or diesel, 
especially designed or adapted for marine use. 

marine radiotelephone 

VHF-FM radio; an important safety factor in emergencies. 

mark 

A visual aid to navigation. Often called navigation mark, 
includes floating marks (buoys) and fixed marks (bea¬ 
cons). 

marlinspike 

An iron spike for opening the strands of a rope while 
splicing. 

marlinspike seamanship 

The art of handling and working all kinds of fiber, synthetic 
and wire rope; includes every variety of knotting, splicing, 
worming, parceling, serving, and fancywork. 

masking 

Obscuration of an object. Radar masking (also radar shadow) 
refers to a phenomenon in which a target is obscured 
(masked) by virtue of its location behind another larger 
target—such as a mountain, structure, or other vessel. 
Visual masking can also occur, 
mast 

A spar set upright to support rigging and sails. 

mast step 

The brace on which, or into which, the heel of the mast 
rests. 

master station 

Essential component of a loran-C chain. This station 
broadcasts the signal that is used to identify the chain (the 
GRI) and is the common base against which all time 
differences are calculated, 
mayday (MAYDAY is spoken three times) 

A distress signal given to indicate that a mobile station is 
threatened by grave and imminent danger and requests 
immediate assistance. 


49 




M - 

mean high water (MHW) 

The arithmetic mean of the high water heights observed 
over a specific 19-year cycle. For stations with shorter 
series, simultaneous observational comparisons are made 
with a primary control tide station in order to derive the 
equivalent of a 19-year value, 
mean higher high water (MHHW) 

The arithmetic mean of the higher high water heights of a 
mixed tide observed over a specific 19-year cycle. Only the 
higher high water of each pair of high waters, or the only 
high water of a tidal day is included in the mean, 
mean low water (MLW) 

A tidal datum. The arithmetic mean of the low water 
heights observed over a specific 19-year Metonic cycle (the 
National Tidal Datum Epoch). For stations with shorter 
series, simultaneous observational comparisons are made 
with a primary control tide station in order to derive the 
equivalent of a 19-year value, 
mean low water springs (MLWS) 

Frequently abbreviated spring low water. The arithmetic 
mean of the low water heights occurring at the time of the 
spring tides observed over a specific 19-year cycle, 
mean lower low water (MLLW) 

The arithmetic mean of the lower low water heights of a 
mixed tide observed over a specific 19-year cycle. Only the 
lower low water of each pair of low waters, or the only low 
water of a tidal day is included in the mean, 
mean range of tide 

The difference in height between mean high water and 
mean low water, 
mean sea level (MSL) 

The arithmetic mean of hourly water elevations observed 
over a specific 19-year cycle. Shorter series are specified in 
the name; e.g., monthly mean sea level and yearly mean sea 
level. 

mean tide level (MTL) 

Also called half-tide level. A tidal datum midway between 
mean high water and mean low water. 

mercator projection 

The projection technique most commonly used in naviga- 


50 




tional charts; shapes and distances are increasingly dis¬ 
torted as you move into extreme northern and southern 
areas. This is a cylindrical projection ingeniously modified 
by expanding the scale at increasing latitudes to preserve 
ship’s direction, and angular relationships, 
meridian (geographic meridian) 

A great circle of the earth passing through both the geo¬ 
graphic poles and any given point on the earth’s surface, 
meteorological visibility 

The greatest distance at which a black object of suitable 
dimension could be seen and recognized against the horizon 
sky by day, or, in the case of night observations, could be 
seen and recognized if the general illumination were raised 
to the normal daylight level, 
microsecond 

One millionth of a second, 
midship 

Approximately in the location equally distant from the bow 
and stem. 

mileage number 

A number assigned to aids to navigation which gives the 
distance in sailing miles along the river from a reference 
point to the aid to navigation. The number is used princi¬ 
pally in the Mississippi River System. 

mixed tide 

Type of tide with a large inequality in the high and/or low 
water heights, with two high waters and two low waters 
usually occurring each tidal day. In strictness, all tides are 
mixed but the name is usually applied to the tides interme¬ 
diate to those predominantly semidiurnal and those pre¬ 
dominantly diurnal, 
mizzen 

The after and smaller mast of a ketch or yawl; also a sail set 
on that mast. 

mizzenmast (see mizzen) 

mooring 

An arrangement for securing a boat to a mooring buoy or 
a pier, also anchored. 

mooring buoy 

A buoy secured to a permanent anchor sunk deeply into the 
bottom. 




mooring pennant 

A line with a large eye spliced in the extreme end which is 
permanently attached to a mooring buoy and which is used 
to secure the vessel to the buoy. 

most probable position 

Vessel’s probable position considering all available 
navigational information. Term is generally used when 
there is position uncertainty as a result of conflicting or 
ambiguous information. 

mud 

A general term applied to mixtures of sediments in water. 
Where the grains are less than 0.002 millimeter in diameter, 
the mixture is called clay. Where the grains are between 
0.002 and 0.0625 millimeter in diameter, the mixture is 
called silt. See also sand; stones; rock, definition 2. 
multiple ranges 

A group of two or more ranges, having one of the range 
marks in common. ^ 

mushroom anchor Sr 

A stockless anchor with a cast iron bowl at the end 
of the shank; used principally in large sizes for 
permanent moorings. 



napier diagram 

A graphic plot of the deviation table, 
nautical chart (see chart) 
nautical mile (M) 

One minute of latitude; approximately 6076 feet - about 1/ 
8 longer than the statute mile of 5280 feet. 

nautical slide rule 

Analog device for solving time-speed-distance calcula¬ 
tions. In present manufacture these are typically circular 
slide rules with three separate scales graduated in units of 
time, speed, and distance. 

navigable waters 

The seas and waters which provide a “road” for transpor¬ 
tation between two or more states or to the sea. 







navigation 

The art and science of conducting a boat safely from one 
point to another. 

Navigation Rules 

Regulations governing the movement of vessels in relation 
to each other, formerly “Rules of the Road.” 

Navy stockless (anchor) 

Found principally on large vessels. Because it is 
stockless, it stows conveniently in hawse pipes, 
neap tides or tidal currents 

Tides of decreased range or tidal currents of 
decreased speed occurring semimonthly as the result of the 
moon being in quadrature. The neap range of the tide is the 
average semidiurnal range occurring at the time of neap 
tides, 
neck 

1. A narrow isthmus, cape, or promontory. 2. The land 
between streams flowing into a sound or bay. 3. A narrow 
strip of land which connects a peninsula with the mainland. 
4. A narrow body of water between two larger bodies. 

north geographic pole 

A reference for specifying a position on the earth’s surface, 
at the north end of the earth’s axis. Also called True North. 

north magnetic pole 

The central point of the north end of the earth’s magnetic 
core to which a compass points when it is free of other 
influences. 

north up 

Type of relative motion radar display with own ship at 
center. This is linked to a gyrocompass or fluxgate compass 
to display a continuous north-up picture on PPI. 

Northill 

This anchor has a stock at the crown instead of at the 
| head. The arm is at right angles to the shank and the 
broad flukes are set at an angle carefully designed to 
assure a quick bite and penetration of the bottom. 




N - 

notch filters 

Filters in a loran receiver that are either fixed or capable of 
being tuned to reduce (“notch out”) the effects of interfering 
signals. Some filters (termed “Pac-Man”) filters can 
automatically seek and notch out interfering signals. Typical 
signals that can cause loran interference are listed in the 
Loran-C Handbook. The notch filters on a loran should be 
adjusted for the area of intended cruising to maximize the 
efficiency of the filtering, 
null 

Position of minimum signal strength for directional antenna. 
This position occurs when the directional antenna is 
perpendicular to the radiated signal. The null is used to 
determine the relative bearing in an RDF set. 

o 


oblate spheroid 

Sphere flattened at the poles, resembling a pumpkin. 

occulting light 

A light in which the total duration of light in each period is 
clearly longer than the total duration of darkness and in 
which the intervals of darkness (occultations) are all of 
equal duration. (Commonly used for single-occulting light 
which exhibits only single occultations which are repeated 
at regular intervals.) 

ocean data aquisition system (ODAS) 

Certain very large buoys in deep water for the collection of 
oceanographic and meteorlogical information. All ODAS 
buoys are yellow in color and display a yellow light. 

off shore tower 

Monitored light stations built on exposed marine sites to 
replace lightships. 

off station 

A floating aid to navigation not on its assigned position. 

off the wind 

Sailing downwind (away from the eye of the wind). 

offshore 

In a zone usually considered to lie from the low watermark 
to three miles from the coast. From the shore, for example, 


54 




-p 

a wind blowing offshore. Distant from the shore, such as 
offshore fishing. 

omega 

Electronic navigation system. 

on plane 

As more and more speed is gained, a boat feels as though 
it has “climbed out of its hole,” and it rides up “on plane.” 

ooze 

A soft, slimy, organic sediment covering part of the ocean 
bottom. 

out of tolerance 

A condition in which a loran-C signal or time difference 
exceeds established tolerances. An out-of-tolerance (OOT) 
condition causes the secondary transmitter to blink. 

outboard 

Toward or beyond the boat’s sides, opposite of inboard. A 
detachable engine mounted on a boat’s stem. 

outboard-powered 

The engine is mounted outside the hull on the transom. 

outfall 

The discharge end of a narrow stream, sewer drain, etc. 

outhaul 

A line, or block and tackle, for stretching the foot of a 
sail out along the boom, 
overboard 
Over the side. 


P 


painter 

A line attached to the bow of a small boat for use in towing 
or making fast, 
palisades 

A line of cliffs. 

palm 

A leather fitting placed over the hand to assist in sewing 
heavy material, such as canvas, with a needle and thread. 
The broad tip of an anchor fluke, 
pan pan (spoken three times) 

The urgency signal used when the safety of the vessel or 
person is in jeopardy. 


55 




p - 

paraline plotter 

Plotter that has a set of rollers attached to enable the device 
to be moved parallel to itself, and used for the same purpose 
as parallel rules. 

parallel of latitude 

Any of the imaginary lines parallel to the equator and 
representing latitude. 

parallel rules 

An instrument for transferring a line parallel to itself, used 
in chartwork for drawing and measuring courses or bear¬ 
ings. 

passing light 

A low intensity light which may be mounted on the 
structure of another light to enable the mariner to keep the 
latter light in sight when passing out of its beam during 
transit. 

pay out 

To ease out a line, or let it run in a controlled manner. 

peak 

The upper outer comer of a gaff sail, 
pebble (see stone) 

pelorus 

A sighting device, marked off in degrees, used to determine 
relative bearings. 

peninsula 

A section of land nearly surrounded by water. Frequently, 
but not necessarily, a peninsula is connected to a larger 
body of land by a neck or isthmus, 
pennant (sometimes “pendant”) 

The line by which a boat is made fast to a mooring buoy. 
(Sometimes called a “pendant.”) A small flag, most fre¬ 
quently a signal flag, 
perigean tides or tidal currents 

Tides of increased range or tidal currents of increased speed 
occurring monthly as the result of the moon being in 
perigee or nearest the earth. The perigean range (Pn) of tide 
is the average semidiurnal range occurring at the time of 
perigean tides, 
perigee 

Point in the lunar cycle when the moon and the earth are 


56 




closest together. Tides have increased range when the 
moon is in perigee. 

period 

The interval of time between the commencement of two 
identical successive cycles of the characteristic of the light 
or sound signal. 

Personal Flotation Device (PFD) 

A life preserver which, when properly used, will support a 
person in the water. Available in several sizes and types. 

phase code interval 

That interval over which the phase code repeats itself. For 
the loran-C system, phase codes repeat every two GRIs. 

phase coding 

Not discussed in the text, this is a scheme of changing the 
phase of the pulses in a transmitted loran signal to minimize 
pulse-to-pulse sky-wave interference and to reject syn¬ 
chronous interfering signals. Master and secondary trans¬ 
mitters use different phase codes for signal identification, 
pier 

A loading or mooring platform extending at an angle 
(usually a right angle) from the shore. 

pile 

A wood, metal or concrete pole driven into the bottom. 

Craft may be made fast to a pile; it may be used to support 
a pier (see piling) or a float. 

piling 

Support, protection for wharves, piers, etc.; constructed of 
piles (see pile). 

pilot waters 

Areas in which the services of a pilot are recommended or 
required. Also used in a more general sense to denote 
waters in which navigation is done using pilotage/piloting. 

piloting 

Piloting is navigation involving frequent or continuous 
reference to charted landmarks, ATONs, or charted ob¬ 
jects, and depth soundings. 

pinch 

To sail a boat too close to the wind, causing the sails to stall. 

pintle 

The pin-like fittings on the rudder which serve as pivots 
when inserted into the gudgeons which are mounted on the 
transom. 57 




p - 

pitchpoling 

A boat being thrown end-over-end in 
rough seas. 

pivot point 

A point somewhat aft of the bow, 
somewhere forward of the midpoint. To an observer on 
board, a vessel appears to turn about its pivot point, 
plan position indicator (PPI) 

The screen display of a radar, so named because it presents 
a plan view of the area scanned, 
planing 

A boat is said to be planing when it is essentially moving 
over the top of the water. 

planing hull 

A type of hull with flat surfaces (not necessarily horizontal) 
which enable a vessel to climb up its bow wave and to glide 
across the water when it has attained sufficient speed (see 
bow wave). 

plotter 

Device for drawing straight lines on a nautical chart, and 
measuring courses, bearings, and (with some plotters) 
distances. 

plotting sheet 

A blank chart, usually on the Mercator projection, showing 
only the graticule and a compass rose. The meridians are 
usually unlabeled by the publisher so that these can be 
appropriately labeled when the chart is used in any longi¬ 
tude. Plotting sheets are often used in lieu of charts when 
the vessel is “off-soundings” (in deep water), 
point 

One of 32 points of the compass equal to 11- 1/4 degrees. 

point of no return 

The point of no return is the point beyond which there is not 
sufficient fuel on board to return on an out-and-back 
journey using the entire fuel on board, including the 
reserve. 

point system 

A nearly obsolete system of dividing a circle into 32 parts 
of 11-1/4 degrees each, for reference to direction; i.e., 
NNW (337°30’). 



58 




-p 

pollution 

The throwing, discharging, or depositing of any refuse 
matter of any kind (including plastic, trash, garbage, oil, 
and other liquid or solid substances) into the waters. 

polyconic projection 

A map or chart projection in which the earth is projected on 
a series of cones concentric with the earth’s axis and 
tangent to the sphere of the earth. Charts of the Great Lakes 
are typically based on the polyconic projection. 

polyester rope 

A synthetic fiber rope often used for sheets and halyards; 
aka Dacron, Terylene, etc. 

polypropylene rope 

The least costly of the common synthetic ropes; major 
advantage is that it floats. 

pooping 

When the following wake breaks over the stem or poop of 
a boat, and, in some cases, swamps it. 

port 

The left side of a boat looking forward. A harbor. 

port hand mark 

A buoy or beacon which is left to the port hand when 
proceeding in the “conventional direction of buoyage.” 

port tack 

Sailing with the wind coming over the port side of the boat 
causing the main boom to be on the starboard side. 

position 

On the earth this refers to the actual geographic location of 
a vessel defined by two parameters called coordinates. 
Those customarily used are latitude and longitude. Position 
may also be expressed as a bearing and distance from an 
object, the position of which is known, 
position approximate 

Term used on nautical charts to denote an inexact position. 

This term is used principally on charts to indicate that the 
position of a wreck, shoal, or other obstruction has not been 
accurately determined or does not remain fixed. 

position doubtful 

Of uncertain position. This term is used principally on 
charts to indicate that a wreck, shoal, or other obstruction, 
has been reported in various positions and not definitely 
determined. 




p - 

position line (see line of position) 

pram 

A small utility boat (8-10' long) with a wide beam 
relative to its length; used as a tender, 
predictable accuracy 

Term meaning the same as absolute accuracy. 

preferred channel mark 

A lateral mark indicating a channel junction or bifurcation, 
or a wreck or other obstruction which, after consulting a 
chart, may be passed on either side. 

Primary Aid To Navigation 

An aid to navigation established for the purpose of making 
landfalls and coastwise passages from headland to head¬ 
land. 

prime meridian 

The meridian from which longitude 
is measured both east and west; 0° 
longitude. It passes through 
Greenwich, England, and divides the 
earth into Eastern and Western Hemispheres 1 ! 0 
privileged vessel 

A vessel which, according to the applicable Navigation 
Rule, has right-of-way (this term has been superseded by 
the term “stand-on”). 

prohibited area 

An area shown on nautical charts within which navigation 
and/or anchoring is prohibited except as authorized by 
appropriate authority. 

prolate spheroid 

Sphere flattened at the equator, resembling a football. 

promontory 

High land extending into a large body of water beyond the 
line of the coast. Called headland when the promontory is 
comparatively high and has a steep face. 

propeller diameter 

The diameter of the circle circumscribed by the turning 
blades of a propeller. 

propeller pitch 

The distance a propeller would screw itself forward into the 
water on a single complete rotation if the water were a solid 
material and there were no slippage. 



60 




- R 

protractor 

An instrument for measuring angles on a surface, such as 
a chart. Typically a protractor is constructed of transparent 
plastic and has a semicircular scale measured in degrees. 

prowords 

Oral shorthand of common radio words and phrases. 

puff 

A term used to describe a gust of wind, 
pulse repetition frequency 

The average number of pulses per unit of time. 

Q 


quarter 

The sides of a boat aft of amidships, 
quartering sea 

Sea coming on a boat’s quarter. 

quay 

A structure of solid construction along a shore or bank 
which provides berthing and cargo handling facilities for 
ships. A similar facility of open construction is call a wharf. 

quick light 

A light more than 50 but less than 80 flashes per minute. 
(Previously called quick flashing light.) 

R 


race 

A rapid current or a constricted channel in which such 
current flows. 

racon 

Racons are devices placed on certain buoys or other 
ATONs to increase the likelihood of detection and aid 
identification. Racons, when triggered by pulses from a 
vessel’s radar will transmit a coded reply that is displayed 
on the vessel’s PPI. This reply identifies the racon station 
by exhibiting a series of dots and dashes which appear on 
the PPI emanating radially from the racon. All racons 
operate in the marine radar X-Band from 9,300 to 9,500 
Mhz. Some “frequency agile” racons also operate in the 
2,900 to 3,000 Mhz marine radar S-Band. 


61 




R - 

radar 

Self-contained navigation and collision avoidance system 
consisting of a shipboard transmitter and receiver. The 
transmitter transmits briefly, then shuts off to permit the 
receiver to “listen” for the reflected transmission or echo, 
radar bearing 

A bearing obtained with radar, 
radar fix 

A position fix determined by radar alone, or by radar in 
conjunction with some other method for determining a 
LOP. Conventionally, radar fixes can be determined by a 
radar range and bearing from an identified radar conspicu¬ 
ous object, by two ranges from two such objects, or by two 
bearings from two such objects, 
radar range 

1. A range (distance) obtained with radar. 2. The maximum 
distance at which a radar set is effective in detecting targets. 

radar reflectors 

Objects that reflect radar waves very well and which serve 
to increase the size or strength of the radar return. Some 
buoys, for example, are equipped with a radar reflector to 
increase the ease of detection and identification. Radar 
reflectors are also made to carry aboard fiberglass or wood 
vessels to increase the likelihood of detection by other 
radar-equipped vessels, 
radar transfer plotting sheet 

Plotting sheet similar to a maneuvering board used for 
plotting radar targets, 
radio beacons 

Transmitting stations used for RDF system. Marine radio 
beacons operate in the 285 to 325 kilohertz band. As of this 
writing there are two types of radio beacons, continuous 
and sequenced. 

radio direction finding 

Older short-range radio navigation system consisting of a 
series of land-based stations broadcasting in the LF/MF 
band and on-board receivers with directional antennas. Use 
of the directional antenna enables relative bearings to be 
determined, and, by simple conversion, lines of position. 


62 




- R 

radio mast 

A relatively short pole or slender structure for elevating 
radio antennas, usually found in groups. 

radio navigation 

Determining positions using radio waves of known 
characteristics emitted from known locations. Forms include 
LORAN-C, RDF, OMEGA, Satellite systems, etc. 

radio tower 

A tall pole or structure for elevating radio antennas. 

radiobeacon 

An electronic aid to navigation. 

radius of action 

The greatest distance (in an out-and-back voyage) that the 
vessel can travel and still leave sufficient fuel to return 
without drawing down the fuel reserve. 

rake 

The slant of a ship’s funnels, bow, or stem. The fore-and- 
aft slant of a vessel’s mast. 

range 

The distance in nautical miles that the vessel can travel with 
the available fuel on board. The range may or may not 
include an allowance for a fuel reserve. Range is a function 
of throttle setting and other factors. 

range lights 

Two lights associated to form a range which often, but not 
necessarily, indicates a channel centerline. The front range 
light is the lower of the two, and nearer to the mariner using 
the range. The rear range light is higher and further from the 
mariner, 
range of tide 

The difference in height between consecutive high and low 
waters, the mean range is the difference in height between 
mean high water and mean low water. Where the type of 
tide is diurnal the mean range is the same as the diurnal 
range. 

range ring 

Circular line on PPI (either fixed or variable) denoting a 
particular distance from the observer. 


63 




R - 

ranges 

A pair of ATONs placed a suitable distance 
apart, with the far daymark mounted higher 
than the near one. When the range marks 
are in line, the vessel is in the channel. ,, 

Ranges can also be established by any 1 ~~ ~ 

charted objects. - l ~~ —- 

rate 

Generic term sometimes used to describe a loran-C LOP. 
Nautical charts, for example, will identify the “rates” 
shown, e.g., 9960 W, 9960 X, 9960 Y, 9960 Z, 7980 W, etc. 

reach 

The comparatively straight segment of a river or channel 
between two bends. 

ready about 

The preparatory command given before “hard alee” when 
tacking (passing the bow through the eye of the wind). 

real time method 

An alternative radar plotting method that provides a rapid 
means of plotting radar targets. 

rebuilt 

A fixed aid to navigation, previously destroyed, which has 
been restored as an aid to navigation, 
reciprocal bearing or course 

A bearing or course that differs from the original by 180 
degrees. 

reciprocal direction 

Corresponding but reversed direction. 

red sector 

A sector of the circle of visibility of a navigational light in 
which a red fight is exhibited. Such sectors are designated 
by their limiting bearings, as observed at some point other 
than the fight. Red sectors are often located such that they 
warn of danger to vessels, 
reef 

An offshore consolidated rock hazard to navigation at a 
depth of 16 fathoms (30 meters) or less. Also used as a term 
for a low rocky or coral area some of which is above water. 
Also, in sailing; to secure its foot when reefed. 



64 






reeve 

To pass a line through a block or other opening. 

reference station 

A tide or current station for which independent daily 
predictions are given in the Tide Tables and Tidal Current 
Tables, and from which corresponding predictions are 
obtained for subordinate stations by means of differences 
and ratios, 
regulatory mark 

A white and orange aid to navigation with no lateral 
significance. Used to indicate a special meaning to the 
mariner, such as danger, restricted operations, or exclusion 
area. 

relative (R) 

See relative direction, 
relative direction (bearing) 

A direction relative to the fore-and-aft line of a vessel, 
expressed in degrees and labeled “R.” 
relative motion plot 

Typical plot prepared on a maneuvering board to determine 
the point of closest approach and time of closest approach 
of a radar target. 

relighted 

An extinguished aid to navigation returned to its advertised 
light characteristics. 

repeatable accuracy 

Term used with the loran system to measure the repeatabil¬ 
ity of the loran TDs or Lat/Lo at a fixed point. Repeatable 
accuracy is typically much greater than absolute accuracy, 
replaced (temporarily) 

An aid to navigation previously off station, adrift, or 
missing, restored by another aid to navigation of the same 
type and characteristics, 
replaced (Temporarily) 

An aid to navigation previously off station, adrift, or 
missing, restored by another aid to navigation of different 
type and/or characteristic, 
reset 

A floating aid to navigation previously off station, adrift, 
or missing, returned to its assigned position (station). 




R - 

restricted visibility 

Any condition in which visibility is restricted by fog, mist, 
falling snow, heavy rainstorms, sandstorms, or other simi¬ 
lar causes. 

reversing current 

A tidal current which flows alternately in approximately 
opposite directions with a slack water at each reversal of 
direction. Currents of this type usually occur in rivers and 
straits where the direction of flow is more or less restricted 
to certain channels, 
rhumb line 

A line that is formed that spirals around the globe toward 
the nearer pole when a direction (other than due east or due 
west) is specified on the surface of the earth, and followed 
for any distance, so that each subsequent meridian is 
crossed at the same angle relative to the direction of the 
pole. Also called loxodrome. This appears as a straight line 
on a Mercator chart, 
rhythmic light 

A light showing intermittently with a regular periodicity. 

rig 

The arrangement of a boat’s sails, masts and rigging. 

rigging 

The general term for all the lines of a vessel. 

right-handed propeller 

A propeller designed to rotate in a clockwise direction 
(viewed from aft) when driving a boat forward. 

right-of-way 

An obsolete term. Under the 1972 COLREGS, no vessel 
has the “right-of-way” in a meeting situation, and each is 
equally responsible for avoiding collision. 

riprap 

Stones or broken rock thrown together without order to 
provide a revetment, 
roach 

The outward curve at the leech of a sail. 

road 

A open anchorage affording less protection than a harbor. 
Some protection may be afforded by reefs, shoals, etc. 
Often used in the plural, e.g., Hampton Roads. 


66 




R 


rock 

1. An isolated rocky formation or single large stone, 
usually one constituting a danger to navigation. It may be 
always submerged, always uncovered, or alternately cov¬ 
ered and uncovered by the tide. A pinnacle is a sharp- 
pointed rock rising from the bottom. 2. The naturally 
occurring material that forms the firm, hard, and solid 
masses of the ocean floor. Also, rock is a collective term for 
masses of hard material generally not smaller than 256 
millimeters, 
rock awash 

A rock that becomes exposed, or nearly so, between chart 
sounding datum and mean high water. In the Great Lakes, 
the rock awash symbol is used on charts for rocks that are 
awash, or nearly so, at low water datum. 

rode 

An anchor line and/or chain. 

roller furling 

A jib or mainsail rigged to furl by rolling up around its own 
luff. 

roller reefing 

Reducing sail area by winding it on a rotating boom, 
root mean square (RMS) 

The square root of the arithmetical mean of the squares of 
a group of numbers. 

rope 

In general, cordage as it is purchased at the store. When it 
comes aboard a vessel and is put to use it becomes line. 

rotary current 

A tidal current that flows continually, with the direction of 
flow changing through all points of the compass during the 
tidal period. Rotary currents are usually found offshore 
where the direction of flow is not restricted by any barriers. 
The tendency for the rotation in direction has its origin in 
the Coriolis force and, unless modified by location condi¬ 
tions, the change is clockwise in the Northern Hemisphere 
and counterclockwise in the Southern, 
round of bearings 

A group of bearings observed simultaneously, or over a 
short period of time, such as would be used to determine a 
visual fix. 


67 




R - 

rudder 

A vertical plate or board which can be 
pivoted to steer a boat. 

run 

To allow a line to feed freely. 

runabout 

A small, sporty craft intended for general use such as day 
cruising, water skiing, and fishing. 

running 

Sailing before the wind; sailing with the wind astern. 

running fix (RFIX) 

A fix obtained by means of two or more LOPs taken at 
different times and adjusted to a common time. This 
practice involves advancing or retiring LOPs. 

running lights 

Lights required to be shown on boats underway between 
sundown and sunup; indicates location and orientation of 
vessel. 

running rigging 

Sheets, halyards, topping lifts, downhauls, vangs, etc., 
used for raising and adjusting sails (see standing rigging). 

S 



safety signal-radio 

A radio signal used for messages concerning the safety of 
navigation or giving important meteorological warnings 
(pronounced SAY-CURITAY). 

sail plan 

Form and arrangement of the sails on a sailboat, 
sail stops 

A short length of line used to wrap around the sail when it 
is bundled up or furled, 
sailing free 

Sailing with the wind aft (running), 
sails 

Flexible vertical airfoils, generally made of cloth, that use 
wind pressure to propel a boat, 
samson post 

A single bitt in the bow or stem of a boat, secured to a 
structural member, usually the keel. 


68 







-s 

sand 

Sediment consisting of small but easily distinguishable 
separate grains between 0.0625 and 2.0 millimeters in 
diameter. It is called very fine sand if the grains are 
between 0.0625 and 0.125 millimeter in diameter, fine 
sand if between 0.125 and 0.25 millimeters, medium sand 
if between 0.25 and 0.50 millimeters, coarse sand if 
between 0.50 and 1.0 millimeters, and very coarse sand if 
between 1.0 and 2.0 millimeters. See also mud, stones, 
rock, definition 2. 

SATNAV 

Satellite navigation system. 

Scalar 

A scalar is a quantity that has magnitude only—in contrast 
to a vector which has both quantity and direction. Velocity, 
for example, is a vector because, properly speaking, it has 
both quantity (e.g., 10 knots) and direction (e.g., 045 
degrees). Throttle setting, measured in revolutions per 
minute for example, is a scalar quantity because it has 
magnitude only, 
scope 

The ratio of the length of anchor line deployed to the depth 
of the water, including the distance from the vessel’s bow 
to the water, 
screw 

A boat’s propeller. 

sculling 

Moving the tiller or an oar back and forth to propel a boat 
ahead. 

sea anchor 

Any device used to reduce a 
boat’s drift before the wind. 

Compare with DROGUE. 

sea room 

A safe distance from the shore or other hazards, 
seaman's eye 

Navigation by informal means made possible by thorough 
familiarity with the area of operations, 
seaworthy 

A boat or a boat’s gear able to meet the usual sea conditions. 



69 




s - 

secondary coding delay 

Interval in microseconds between the reception of a loran 
signal at the secondary station and the time when the 
secondary station transmits a signal in the loran navigation 
system. Secondary coding delays are published for each 
secondary station, 
secondary station 

One of the two to four other transmitters in the loran-C 
chain (designated W, X, Y, and Z) that transmits a signal, 
keyed in time to that of the master, used to compute a time 
difference. At one time, the secondary transmitter would 
transmit (after an interval known as the secondary coding 
delay) only on receipt of the master signal. Now, the 
secondary transmitters maintain their own time standard, 
but the time of transmission relative to the master signal is 
designed to be the same as before, 
sector (see light sector) 
secure 

To make fast. 

security (see safety signal-radio) 
seize 

To bind two lines together with tight tine. 

semidiurnal 

Having a period or cycle of approximately one-half of a 
tidal day. The predominating type of tide throughout the 
world is semidiurnal, with two high waters and two low 
waters each tidal day. The tidal current is said to be 
semidiurnal when there are two flood and two ebb periods 
each day. 
set 

The direction towards which the current is flowing ex¬ 
pressed in degrees. This term is also commonly used to 
mean the direction towards which a vessel is being deviated 
from an intended course by the combined effects of exter¬ 
nal force such as wind and current, 
set flying 

Said of a sail made fast only at its comers, such as a 
spinnaker. 

72 COLREGS (see COLREGS) 


70 




-s 

sextant 

Device for precise measurement of horizontal or vertical 
angles. 

shackle 

A “U” shaped connector with a pin or bolt across the open 
end. 
sheave 

The grooved wheel or roller in a block (pulley). 

sheer 

The fore-and-aft curvature of the deck as shown in side 
elevation, 
sheet 

The line used to control the forward or athwartships 
movement of a sail. 

sheet bend 

A bend used to join two ropes of unequal size. 

Functionally different from a square knot in that 
it should be used between lines of different 
diameters. 

ship 

A larger vessel usually thought of as being used for ocean 
travel. A vessel able to carry a “boat” on board. 

ship’s head up 

Type of relative motion radar display with own ship in 
center and instantaneous relative bearings of targets dis¬ 
played, 
shoal 

An offshore hazard to navigation at a depth of 16 fathoms 
(30 meters) or less, composed of unconsolidated material. 

shoal water 

Shallow water or water over a shoal. 

short legs 

Slang expression to denote a vessel with a limited fuel 
capacity in relation to its fuel consumption. Opposite: long 
legs. 

short splice 

A method of permanently joining the ends of two ropes. 

shroud 

The standing rigging that supports the mast at the sides of 
the boat. 



71 




s - 

signal-to-noise ratio (SNR) 

The ratio of the signal strength to that of the electronic noise 
of a signal. Loran coverage diagrams are calculated so that 
the SNR is at least 1:3, even though many receivers are 
capable of processing weaker signals. Signal to noise is 
sometimes expressed in decibels (DB). The SNR in decibels 
is mathematically equal to 20 log (SNR), so that an SNR of 
1:3 works out to approximately -9.54. 
silt (see mud) 
siren 

A sound signal which uses electricity or compressed air to 
actuate either a disc or a cup-shaped rotor. 

skeleton tower 

A tower, usually of steel, constructed of heavy comer 
members and various horizontal and diagonal bracing 
members, 
skiff 

A utility boat, flat-bottomed with either straight or slightly 
flared sides, 
skywave 

Skywave is an indirect radio wave that reflects off the 
ionosphere, rather than traveling a direct path from trans¬ 
mitter to receiver. Because these waves travel a different 
distance (in particular a longer distance), sky waves will 
give an erroneous TD reading in a loran receiver. The shape 
of the loran pulse and phase coding are used to attempt to 
minimize or eliminate the effects of skywave contamina¬ 
tion. 

skywave delay 

The time interval between the arrival of the groundwave 
and the various skywave reflections. Typically, skywaves 
can arrive as early as 35 microseconds, or as late as 1,500 
microseconds after the groundwave. 
slack 

Not fastened; loose. Also, to loosen. Also the interval of no 
current movement between ebb and flow. 

slack water 

The state of a tidal current when its speed is near zero, 
especially the moment when a reversing current changes 
direction and its speed is zero. The term is also applied to 
the entire period of low speed near the time of turning of the 
current when it is too weak to be of any practical impor- 


72 





with working sails 
and aft. 


tance in navigation. The relation of the time of slack water 
to the tidal phases varies in different localities. For standing 
tidal waves, slack water occurs near the times of high and 
low water, while for progressive tidal waves, slack water 
occurs midway between high and low water, 
slides 

The hardware which attaches either the foot or the luff of 
the sail to a track on the respective spar. 

slime 

Soft, fine, oozy mud or other substance of similar consis¬ 
tency. 

sloop 

A single-masted vessel 
(main and jib) set fore 

slug 

A fitting which is inserted into a groove on either the mast 
or the boom providing attachment for either the luff or the 
foot of the sail respectively. 

small circle 

Any plane passing through the earth, but not through its 
center, produces a small circle at its intersection with the 
earth’s surface. 

snatch block 

A block that opens at the side to allow a line to be inserted 
or removed without reeving the entire length of line. 

solar day 

The duration of one rotation of the earth on its axis, with 
respect to the sun. 
sole 

Cabin or saloon floor. Timber extensions on the bottom of 
the rudder. Also the molded fiberglass deck of a cockpit. 

sound 

A relatively long arm of the sea or ocean forming a channel 
between an island and a mainland or connecting two larger 
bodies of water, as a sea and the ocean, or two parts of the 
same body but usually wider and more extensive than a 
strait. The term has been applied to many features which do 
not fit the accepted definition. Many are very large bodies 
of water, such as Mississippi Sound and Prince William 
Sound, others are mere salt water ponds or small passages 
between islands. 73 







sound signal 

A device which transmits sound, intended to provide 
information to mariners during periods of restricted visibil¬ 
ity and foul weather. 

sounding 

A measurement of the depth of water. 

South Geographic Pole 

A reference for specifying a position on the earth’s surface, 
at the south end of the earth’s axis. Also called True South 
Pole. 

South Magnetic Pole 

The end of the earth’s magnetic core opposite the North 
Magnetic Pole. (Located in Antarctica.) 
spar 

A general term for masts, yards, booms, etc. 

special purpose buoy 

A buoy having no lateral significance used to indicate a 
special meaning to the mariner, such as one used to mark 
a quarantine or anchorage area, 
speed (S) 

The rate at which a vessel advances relative to the water 
over a horizontal distance. When expressed in terms of 
nautical miles per hour, it is referred to as knots (kn or kt). 
One knot equals approximately 1.15 statute miles per hour, 
speed curve 

A curve relating the vessel’s speed through the water to the 
engine’s throttle setting expressed in revolutions per minute 
(RPM). 

speed LOP 

An LOP situated at approximately right angles to the 
intended track, so named because the EP derived from this 
LOP provides a good indication of the vessel’s SMG. 
speed made good (SMG) 

Indicates the overall speed actually accomplished relative 
to the ground along the course line, 
speed of advance (SOA) 

Indicates the speed intended to be made relative to the 
ground along the track line. 

speed of relative motion 

Apparent speed of the target on a radar display, determined 
from the relative motion plot. 




-s 

speed over the ground (SOG) 

The actual speed made good at any instant in time with 
respect to the ground along the course being steered, 
speed through the water (STW) 

The apparent speed indicated by log-type instruments or 
determined by use of tachometer and speed curve or table, 
at a particular point in time, along the course line. 
Speed-Time-Distance 

A formula to calculate speed, time, or distance. 

Spherical Coordinate System 

The system used to define positions on the earth’s surface, 
spinnaker 

A large, light-weather headsail used for running or reach¬ 
ing. 

spire 

A slender pointed structure extending above a building. It 
is seldom less than two-thirds of the entire height of the 
structure, and its lines are rarely broken by stages or other 
features. The term is not applied to a short pyramid-shaped 
structure rising from a tower or belfry. 

spit 

A small tongue of land or a long narrow shoal (usually 
sand) extending from the shore into a body of water. 

splice 

To permanently join two ropes by tucking their strands 
alternately over and under each other. 

spoil area 

Area used for depositing dredged materials, usually near 
and parallel to dredged channels. Spoil areas are shown on 
charts because these may present hazards to navigation for 
even the smallest craft. 

spreader 

A horizontal strut used to increase ^ 
the angle at which the shrouds ap¬ 
proach the mast. £ 

spring line 

A fore-and-aft line used in docking, 
undocking, or to prevent the boat 
from moving forward or astern while 
made fast to a dock. 



75 









s 


spring tide or tidal currents 

Tides of increased range or tidal currents of increased speed 
occurring semimonthly as the result of the moon being new 
or Ml. The spring range of tide is the average semidiurnal 
range occurring at the time of spring tides. 

squall 

A sudden, violent wind often accompanied by rain. 

square knot 

A knot used to join two lines of similar size. Also called a 
reef knot, 
stack 

A tall smokestack or chimney. The term is used when the 
stack is more prominent as a landmark than accompanying 
buildings. 

stadimeter 

An instrument for determining the distance to an object of 
known height by measuring the angle, at the observer, 
subtended by the object. The instrument is graduated 
directly in distance. 

stand of tide 

Sometimes called a platform tide. An interval at high or 
low water when there is no sensible change in the height of 
the tide. The water level is stantionary at high and low water 
for only an instant, but the change in level near these times 
is so slow that it is not usually perceptible, 
stand-on vessel 

That vessel which continues its course in the same direction 
at the same speed during a crossing or overtaking situation, 
unless a collision appears imminent. (Was formerly called 
“the privileged vessel.”) 

standard time 

A kind of time based upon the transit of the sun over a 
certain specified meridian, called the time meridian, and 
adopted for use over a considerable area. With a few 
exceptions, standard time is based upon some meridian 
which differs by a multiple of 15° from the meridian of 
Greenwich. 

standardized color coding (charts) 

Standardized colors used to show loran-C lines of position 
on nautical charts. These color codes for the various 


76 




secondaries in the loran chain are W=blue, X=magenta, 
Y=black, and Z=green. 

standing part 

That part of a line which is made fast. The main part of a line 
as distinguished from the bight and the bitter end. 

standing rigging 

The permanent shrouds and stays that support the mast. 

standpipe 

A tall cylindrical structure, in a waterworks system, the 
height of which is several times the diameter. 

starboard 

The right side of a boat when looking forward. 

starboard hand mark 

A buoy or beacon which is left to the starboard side 
when proceeding in the “conventional direction of 
buoyage.” 

starboard tack 

Sailing with the wind coming over the starboard side of 
the boat and with the boom out over the port side of the 
boat. 

station buoy 

An unlighted buoy set near a Large Navigation Buoy or 
an important buoy as a reference point should the 
primary aid to navigation be moved from its assigned 
position. j \ 

station pointer (see three arm protractor) / \ 

stay Y \ 

That part of the standing rigging supporting / y- 1 
the mast from forward and aft. / \ 

staysail / \ 

A sail (usually triangular) set on one of the 
stays. yT 

stem VtY-" 

The foremost upright timber of a vessel to which the keel 
and ends of the planks are attached. The forwardmost part 
of the bow. 
step 

A socket in the bottom of the boat which receives the lower 
end of the mast. 





stern 

The after part of the boat. 

stern line 

A docking line leading from the stem, 
stock 

The cross bar of an anchor, 
stones 

A general term for rock fragments ranging in size from 2 to 
256 millimeters. An individual water rounded stone is 
called a cobble if between 64 to 256 millimeters, a pebble 
if between 4 and 64 millimeters, and gravel if between 2 
and 4 millimeters. These specialized terms of art are used 
on nautical charts to describe the quality of the bottom, 
storm anchor 

A third anchor for use in really heavy weather. 

storm sails 

Small sails for heavy weather sailing, 
stow 

To put an item in its proper place, 
strait 

A relatively narrow waterway, usually narrower and less 
extensive than a sound, connecting two larger bodies of 
water. 

stratus clouds 

Air masses that are lifted gently and evenly form clouds 
that are even, flat, and layered. 

strength of current 

Phase of tidal current in which the speed is a maximum; 
also the speed at this time. Beginning with slack before 
flood in the period of a reversing tidal current (or minimum 
before flood in a rotary current), the speed gradually 
increases to flood strength and then diminishes to slack 
before ebb (or minimum before ebb in a rotary current), 
after which the current tu ms in direction, the speed increases 
to ebb strength and then diminishes to slack before flood, 
completing the cycle, 
submerged rock 

A rock covered at the chart sounding datum and considered 
to be potentially dangerous to navigation. See also bare 
rock, rock awash. 




T 


subordinate current station 

(1) A current station from which a relatively short series of 
observations is reduced by comparison with simultaneous 
observations from a control current station. (2) A station 
listed in the Tidal Current Tables for which predictions are 
to be obtained by means of differences and ratios applied 
to the full predictions at a reference station, 
subordinate tide station 

(1) A tide station from which a relatively short series of 
observations is reduced by comparison with simultaneous 
observations from a tide station with a relatively long series 
of observations.—(2) A station listed in the Tide Tables for 
which predictions are to be obtained by means of differences 
and ratios applied to the full predictions at a reference 
station. 

supercharging 

A higher performance out of a given-sized engine. 

swamp 

To fill with water, but not settle to the bottom, 
swells 

After the deep water waves are generated far out at sea, they 
move outward, away from their wind source, in ever- 
increasing curves, and become swells. 

swing keel 

A weighted extension of the keel which can be partially 
retracted into the hull or locked in the fully lowered 
position. 

swing ship 

A systematic procedure for adjusting a compass and/or 
developing a deviation curve for a compass aboard a vessel, 
syzygy 

Alignment of earth, moon, and sun where the earth, moon 
and sun are aligned, and the moon and sun are on the same 
side of the earth. Tides have larger ranges (termed spring 
tides) when this condition exists. 


tabernacle 

A hinged fitting at the base of the mast to 
enable the mast to be easily raised or lowered. 



79 





tabling 

An extra thickness of cloth sewn around the sail’s edges 
and at the comers. 

tachometer 

An instrument that indicates the speed of the engine 
measured in revolutions per minute (RPMs). 
tack 

To come about; the lower forward comer of a sail; sailing 
with the wind on a given side of the boat, as starboard or 
port tack, 
tacking 

Moving the boat’s bow through the wind’s eye from close- 
hauled on one tack to close-hauled on the other tack. Same 
as coming about, 
tackle 

A combination of blocks and line rigged to increase 
mechanical advantage. 

tank 

1. A water tank elevated high above the ground by a tall 
skeletal framework. The expression “gas tank’’ or “oil 
tank” is used for the distinctive structures described by 
these words. 2. Sailing term: A fitting on a spar to which 
standing rigging is secured, 
target 

Object seen on a radar screen. If the object is known, it is 
so identified. If not, targets are often given letter designa¬ 
tions for plotting purposes, e.g., target alpha, bravo, Charlie, 
delta, etc. 

three-arm protractor 

An instrument consisting essentially of a circle graduated 
in degrees, to which is attached one fixed arm and two arms 
pivoted at the center and provided with clamps so that these 
can be set at any angle to the fixed arm, within the limits of 
the instrument. It is used for finding a ship’s position when 
the angles between three fixed and known points are 
measured. Also termed a station pointer, 
thwart 

A seat or brace running laterally across a boat. 

thwartships 

At right angles to the centerline of the boat. 




Tidal Current Tables 

Tables which give daily predictions of the times and speeds 
of the tidal currents. These predictions are usually supple¬ 
mented by current differences and constants through which 
additional predictions can be obtained for numerous other 
places. 

tidal difference 

Difference in time or height of a high or low water at a 
subordinate station and at a reference station for which 
predictions are given in the Tide Tables. The difference, 
when added or subtracted from the prediction at the refer¬ 
ence station, gives the corresponding time or tide height for 
the subordinate station, 
tide 

The periodic rise and fall of the water resulting from 
gravitational interactions between the sun, moon, and 
earth. The vertical component of the particulate motion of 
a tidal wave. 

Tide Tables 

Tables which give daily predictions of the times and 
heights of high and low waters. These predictions are 
usually supplemented by tidal differences and constants 
through which additional predictions can be obtained for 
numerous other places, 
tiller 

A bar or handle for turning a boat’s rudder or an outboard 
motor. 

time difference 

In the loran system, the time difference (in microseconds) 
between the receipt of the master and secondary signals. 

time meridian 

A meridian used as a reference for time. 

time to go (TTG) 

Calculated time until the next waypoint is reached, ob¬ 
tained by dividing the distance to go by the groundspeed. 

toggles 

Small fittings which allow the tumbuckle to lie in the same 
straight line as the stay or shroud to which it is fitted. Also, 
a pin through eye or bight of rope used as a quick release. 




T - 

topmark 

One ormore relatively small objects of characteristic shape 
and color placed on an aid to identify its purpose. 

topping lift 

A line used to support the weight of, or to adjust the 
horizontal set of, a spar such as a boom or a spinnaker pole, 
topsides 

The sides of a vessel between the waterline and the deck. 
On or above the deck. 

tornado 

A very tight vortex of wind, usually a mile or less in 
diameter. 

tower 

A structure with its base on the ground and high in 
proportion to its base, or that part of a structure higher than 
the rest, but having essentially vertical sides for the greater 
part of its height, 
track (TR) 

The intended or desired horizontal direction of travel with 
respect to the ground. (Synonym: Intended Track, 
Trackline.) 

tracking 

Process of moving towards a location by adjusting the 
heading to compensate for prevailing current so as to travel 
to the station in a straight line, 
tracking (loran) 

The process of measuring time differences from an acquired 
master-secondary loran-C pair. The signal-to-noise ratio 
required for tracking of a preidentified signal is generally 
less than that required for signal acquisition. For this reason 
it is sometimes the case that a vessel that has already 
acquired a loran signal can continue to navigate with this 
signal although an identical receiver turned on may be 
unable to acquire the signal, 
transducer 

A device that converts one type of energy to another, as a 
loudspeaker that changes electrical energy into acoustical 
energy. 


82 




transit 

British term for range, see range. 

transom 

The stem cross-section of a square -stemed boat. 

traveler 

A device that allows sheets to slide athwartships. 

trawler 

A general term to describe a vessel with a displacement or 
semi-displacement hull designed for long distance cruis¬ 
ing. Trawlers often resemble fishing vessels. 

trim 

Fore and aft balance of a boat. 

tropic currents 

Tidal currents occurring semimonthly when the effect of 
the moon’s maximum declination is greatest. At these 
times the tendency of the moon to produce a diurnal 
inequality in the current is at a maximum. 

tropic tides 

Tides occurring semimonthly when the effect of the moon’s 
maximum declination is greatest. At these times there is a 
tendency for an increase in the diurnal range. 

True North Pole 

The north end of the earth’s axis. Also called North 
Geographic Pole. The direction indicated by 000° (or 360°) 
on the true compass rose. 

true rose 

The resulting figure when the complete 360° directional 
system is developed as a circle with each degree graduated 
upon it, and with the 000° indicated as true north. Also 
called compass rose. 

True South Pole 

A reference for specifying a position on the earth’s surface, 
at the south end of the earth’s axis. Also called South 
Geographic Pole. 

true wind 

The direction from which the wind is blowing. 

trunk 

The structure which houses the centerboard; also an en¬ 
closed passageway. 




turnbuckle 

A threaded fitting to pull two eyes together for 
adjustment of standing rigging. 

turning bearing 

A bearing on a charted object, measured in 
advance by the navigator, at which the ves¬ 
sel should turn to reach the next leg of the course. 

turning buoy 

A buoy marking a turn, as in a channel, 
twin propellers (screws) 

A boat equipped with two engines. 

two-stroke engine 

Gasoline engine having two working chambers. 

type of tide 

A classification based on characteristic forms of a tide 
curve. Qualitatively, when the two high waters and two low 
waters of each tidal day are approximately equal in height, 
the tide is said to be semidiurnal; when there is a relatively 
large diurnal inequality in the high or low waters or both, 
it is said to be mixed; and when there is only one high water 
and one low water in each tidal day, it is said to be diurnal. 

u 

uncorrecting (a magnetic direction) 

Converting a true direction to equivalent magnetic or 
compass direction. 

uncovered 

Above water, the opposite of submerged. 

underway 

A vessel not at anchor, made fast to a pier or wharf, or 
aground. 

Uniform State Waterway Marking System (USWMS) 
A system of marks to supplement the federal system in 
marking of state waters; a system of regulatory markers to 
warn a vessel operator of dangers and to provide general 
information and directions, 
unmanned light 

A light which is operated automatically. 







unreeve 

To run a line completely through and out of a block. 

upper shrouds 

The shrouds which run from the chain plates at the sides of 
the boat over the spreaders to the masthead, 
urgency signal-radio 

See PAN PAN (pronounced PAHN PAHN). 

utility outboard 

A boat specifically designed for outboard motors. 

v 


V bottom 

A hull with the bottom section 
in the shape of a “V.” 
vang (see boom vang) 

vanishing tide 

In a mixed tide with very large diurnal inequality, the lower 
high water (or higher low water) frequently becomes 
indistinct (or vanishes) at time of extreme declinations. 
During these periods the diurnal tide has such overriding 
dominance that the semidiurnal tide, although still present, 
cannot be readily seen on the tide curve, 
variable range marker 

An adjustable range ring in a PPI that can be moved to 
measure the range of a target. 

variation 

The angular difference between the magnetic meridian and 
the geographic meridian at a particular location. 

varsol 

A liquid used in the bowl of a compass to damp the card’s 
excessive motion and reduce response to a slower, more 
readable, gentle rotation and to lubricate the bearing on the 
pivot. 

vector (see scalar) 

ventilation system 

A system for the purpose of conveying air into each engine 
and fuel tank compartment and exhausting dangerous 
vapors out of the vessel. 




V 


very high frequency radio (VHF) 

Radio frequency of 30 MHz to 300 MHz. The VHF 
system is essentially a line-of-sight system limited in 
range to only a little beyond the horizon, 
vigia 

A rock or shoal of uncertain position or existence. The 
same term is used to describe a printed warning to that 
effect 

visual aid to navigation 

An aid to navigation which transmits information 
through its visual observation. It may be lighted or 
unlighted. 

visual distress signal (VDS) 

A signal to attract attention and to guide rescuers in a 
search-and-rescue situation, 
voyage fuel (see enroute fuel) 

w 


wake 

Moving waves, track or path that a boat leaves behind it 
when moving across the waters. 

watching properly 

An aid to navigation on its assigned position exhibiting the 
advertised characteristics in all respects. 

waterline 

A line painted on a hull which shows the point to which a 
boat sinks when it is properly trimmed (see BOOT TOP). 

water tower 

A structure enclosing a tank or standpipe so that the 
presence of the tank or standpipe may not be apparent. 

wave height 

The vertical distance between the crest and the trough of a 
wave. 

wave length 

The distance between consecutive crests of a wave. 

wave shape 

The height and length of the wave as it travels. 


86 




w 


way 

Movement of a vessel through the water such as headway, 
stemway or leeway. 

waypoint 

Arbitrary geographic point entered into a loran set as a 
reference point for navigational calculations. Typically 
voyages are organized into a series of waypoints marking 
the legs of the trip. 

waypoint sequencing (route option) 

A feature incorporated into many loran receivers that 
allows an operator to store a sequence of waypoints in the 
loran’s memory to describe a route. In this mode, whenever 
the vessel arrives at a waypoint the next waypoint in a 
prestored route sequence automatically appears on the 
display screen, 
weather helm 

The tendency of a boat to turn into the wind when its rudder 
is set amidships, 
weather side 

Windward side of a boat. 

weighing anchor 

Raising the anchor when preparing to get underway. 

wharf 

A man-made structure bounding the edge of a dock and 
built along or at an angle to the shoreline, used for loading, 
unloading, or tying up vessels, 
wheel 

A circular frame with an axle attached to the rudder of a 
vessel used for steering. Also a slang expression for a 
propeller. 

whipping 

The act of wrapping the end of a piece of rope to prevent it 
from fraying. 

whisker pole 

A spar used to extend the jib when running. 

whistle 

A wave-actuated sound signal on buoys which produces 
sound by emitting compressed air through a circumferen¬ 
tial slot into a cylindrical bell chamber. 


87 




w- 

white water 

Foaming, whitish water, as in whitecaps, rapids, etc. A 
light-colored water over a shallow area. 

winch 

A device to increase hauling power when raising or trim¬ 
ming sails. 

wind of motion 

That wind which is perceived on a boat as the result of the 
movement of the boat itself. 

windward 

Toward the direction from which the wind is coming, 
wing and wing 

Running with the mainsail 
set on one side of the boat 
and the jib set on the other 
side. 

wing dam 

A dam constructed to maintain a clear channel and control 
the random meandering of sandbars. 

winter light 

A light which is maintained during those winter months 
when the regular light is extinguished, it is of lower 
candlepower than the regular light but usually of the same 
characteristic. 

winter marker 

An unlighted buoy without sound signal, used to replace a 
conventional buoy when that aid to navigation is endan¬ 
gered by ice. 

withdrawn 

The discontinuance of a floating aid to navigation during 
severe ice conditions or for the winter season. 

working sails 

Sails for use under normal conditions; on a sloop, the 
mainsail and jib. 
wreck 

The ruined remains of a vessel which has been rendered 
useless, usually by violent action, as by the action of the sea 
and weather on a stranded or sunken vessel. In hydrography 
the term is limited to a wrecked vessel, either submerged or 



Running Wing and Wing 


88 







visible, which is attached to or foul of the bottom or cast up 
on the shore. 

wreck buoy 

A buoy marking the position of a wreck. It is usually placed 
on the seaward or channel side of the wreck and as near to 
the wreck as conditions will permit. To avoid confusion in 
some situations, two buoys may be used to mark the wreck. 
The possibility of the wreck having shifted position due to 
sea action between the times the buoy was established and 
later checked or serviced should not be overlooked. Also 
called wreck-marking buoy. 

Y 


yachtsman's anchor 

The plane of the stock is perpendicular to that of 
the arm and the stock is at the head; it has a sharp 
bill for good penetration of the bottom; and the 
fluke is diamond-shaped to permit the cable to 
slip past it without fouling, 
yaw 

To swing off course, as when due to the impact of a 
following or quartering sea. 
yawl 

A two-masted sailboat with the small mizzen mast stepped 
abaft the rudder post. 



z 


zeroing-in 

Approaching a point or object by use of successive ap¬ 
proximations such as in tacking. 


89 




























































Selected Symbols, 
Acronyms & Abbreviations 
of 

U. S. Coast Guard Auxiliary 


A 

ABAND.Abandoned 


ABYC.American Boat 

and Yacht Coun¬ 
cil 

ACN. Advanced Coastal 

Navigation 

ACU.Auxiliary Com¬ 

munications Unit 
ADF.Automatic Direc¬ 

tion Finder 

ADM.Admiral 

ADSO.Assistant District 

Staff Officer 

AFTN. Aeronautical 

Fixed Telecom¬ 
munications Net¬ 
work 

AIDE.Aide to National 

Commodore/Dis¬ 
trict Commodore 
AIM.Academy Intro¬ 

duction Mission 

A1.Alternating 

AM.Amplitude Modu¬ 

lation 

AMOS.Auxiliary Mission 

Objectives System 

ANMS.Automated Notice 

to Mariner’s Sys¬ 
tem 


ANRC.American National 

Red Cross 

ANS.Auxiliary National 

Store 

ANSC.Auxiliary National 

Supply Center 

ASST.Assistant 

ASF.Additional Second¬ 

ary Factor 

AT A.Actual Time of Ar¬ 

rival 

ATD.Actual Time of De¬ 

parture 

ATE.Actual Time Enroute 

ATON.Aids to Navigation 

AUTODIN .Automated Digital 
Network 

AUXFAC ...Auxiliary Facility 

AUXLAM ..AuxiliaryLeadership 
& Management 
Course 

AUXMIN ...Auxiliary Adminis¬ 
tration Specialty 
Course 

AUXMIS.... Auxiliary Manage¬ 
ment Information 
System 

AUXOP.A designation for a 

member completing 
the seven Auxiliary 
specialty courses. 

AX.AUXOP 



91 





























B 


BA.Branch Assistant 

BC.Branch Chief 

BCN. Basic Coastal Navi¬ 

gation 


BC-NCD.... Branch Chief, Con¬ 
ference Registration, 
National Commo¬ 
dore’s Staff 

BC-NCO.... Branch Chief, Con¬ 
ference Organiza¬ 
tion, National 
Commodore’s Staff 

BC-NCP ....Branch Chief, Con¬ 
ference Planning 

BC-NCR ....Branch Chief, Con¬ 


ference Review 

BC-NCS.Branch Chief, Con¬ 

ference Support 

BCQ.Boat Crew Qualifi¬ 

cation 

BED.Base Enrollment 

Date 

BG.Brigadier General 

(USA) 

BIA.Boating Industry As¬ 

sociations 

bl.Blast 

Bids.Boulders 

BOAT-US.. Boat Owners 

Association* ! 
of U. S. 

BOCA.Boat Owners Coun¬ 

cil of America 

BOS.Boating Safety 

BOSAF.Boating Safety Cor¬ 

respondence Course 
BOSDET ...Boating Safety De¬ 
tachment 


BOSTEAM Boating Safety Team 


BQ.Basically Qualified 

brg .Bearing 

BRIGEN....Brigadier General 
(USAF, USMC) 

BS&S. Boating Skills and 

Seamanship 

BSAC.Boating Safety Ad¬ 

visory Council 
(NBSAC) 

BSC.Boating Safety Cir¬ 

cular 

BY.Buoy 

BYBB.Backyard Boat 

Builders 

C 

C.Can 

C.Canadian 

C.Compass 

C.Course 

CANCON ..Central Area Na¬ 
tional Conference 
CAP.Civil Administrative 


Penalties or 


.Civil Air Patrol 

CAPT.Captain (USCG, 

USN) 

CB.Citizen’s Band Ra¬ 

dio 

CBDR.Constant Bearing 

Decreased Range 

CC.Career Candidate 

CCA.Current Correction 

Angle 

CDA.Current Drift Angle 

CDI.Course Deviation In¬ 

dicator 


CDM VT Compass, Deviation, 

Magnetic, Variation, 
True 






































CDR.Commander 

CFR.Code of Federal 

Regulations 

CG.Coast Guard 

CGAUX.Coast Guard Auxil¬ 

iary 

CH.Channel 

CHDIRAUX 

.Chief Director, Aux¬ 
iliary (Headquarters) 
Cl.Communications In¬ 

spector 

CM.Communications 

CMC.Merchant Marine 

Safety Counsel 

CME. Courtesy 

Marine Ex¬ 
amination 

CMG.Course Made 

Good 

COA.Course of Advance 

COG.Course OverGround 

COL.Colonel 

COLREGS Collision Regula¬ 
tions (NAVRULES) 

COM.Committee 

COMDTINST 

.Commandant In¬ 
struction 

COMMO... Commodore 


COP.Circle of Position 

CPA.Closest Point of Ap¬ 

proach 

CPO.Chief Petty Officer 

CPT.Captain (USA, 

USAF) 

CRC.Civil Rights Coun¬ 

selor 

Cup.Cupola 


CWO.Chief Warrant Offi¬ 

cer 

cy, cl.Clay 

D 

D.Distance 

D.Doubtful 

D.Drift (not preferred) 

D-AA.Administrative As¬ 

sistant to District 
Commodore 

D-AD.District 

Commodore’s Aide 

DBD.Dayboard 

DBN.Daybeacon 

DC-A.Department Chief- 

Public Affairs 

DC-E.Department Chief- 

Education 

DC-F.Department Chief- 

Comptroller 

DC-I.Department Chief- 

Information Systems 

DC-L.Department Chief- 

Legal Affairs 

DC-M.Department Chief- 

Member Resources 

DC-0.Department Chief- 

Operations 

DC-T.Department Chief- 

Training 

DC-V.Department Chief- 

Vessel Examination 
DCO.District Commodore 


DCO-AA....Administrative As¬ 
sistant to District 
Commodore 

DCO-AD.... Aide to District Com¬ 
modore 

DCP.Division Captain 


& 
—V 


93 
















































DEP. 

.. Deputy, Departure 

dev .. 

.. Deviation 

DF. 

.. Direction Finding 

Dflt. 

.. Drift (preferred) 

DIRAUX.., 

.. Director of Auxiliary 
(District or Region) 

DISC. 

.. Discontinued 

DIST. 

.. District 

DIV. 

.. Division 

DIW. 

.. Dead in the Water 

DMA. 

..Defense Mapping 
Agency 

DMAHTC 

.Defense Mapping 
Agency, Hydro- 
graphic, Topographic 
Center 

DOT. 

.. Department of Trans- 
portation 

DR. 

.. Dead Reckoning 

DRM. 

.. Direction of Relative 
Motion 

DSO. 

.. District Staff Officer 

DVC_ 

.. Division Chief 

DVC-NC.. 

.. Division Chief, Con¬ 
ference Coordina¬ 
tion, National Com¬ 
modore’s Staff 

E 

E. 

..East 

E. 

..Estimated 

EANCON 

..Eastern Area Na¬ 
tional Conference 

EBL. 

..Electronic Bearing 
Line 

EBM. 

..Electronic Bearing 
Marker 

ec . 

..Eclipse 

ED. 

.. Existence Doubtful 

EDT. 

..Eastern Daylight 
Time 


EMER CHAR 


.Emergency Charac¬ 
teristics 

ENR.Enroute 

ENS.Ensign 

EP.Estimated Position 

EPIRB.Emergency Position 

Indicating Radio 
Beacon 

EST.Eastern Standard 

Time 

ETA.Estimated Time of 

Arrival 

ETD.Estimated Time of 

Departure 

ETE.Estimated Time 

Enroute 

ev.Every 


EXCOM ....District Executive 
Committee 

F 


F.Flashing 

Fl(2).Group flashing 

FA A.Federal Aviation Ad¬ 

ministration 

FAR.Federal Aviation 

Regulations 

FC.Flotilla Commander 

FED.Flotilla Enrollment 

Date 

1LT.First Lieutenant, 

(USA) 

IstLT.First Lieutenant 

(USAF, USMC) 

fl .Flash 

FI.Flashing 

FM.Frequency Modula¬ 

tion 

FN.Finance 














































FOG SIG INOP 



...Sound Signal Inop- 
erative 

FRM. 

.... Fixed Range Marker 

FS. 

.... Fog signal 

FSO. 

.... Flotilla Staff Officer 

FWPCA.. 

.... Federal Water Pollu- 
tion Control Act 

G 

G. 

.... Gravel 

G. 

...Green 

G-N. 

.... Navigation Safety & 
Waterway Services 

G-NAB.... 

...Auxiliary, Boating, 
and Consumer Af¬ 
fairs Division 

G-NAB-1 

...Auxiliary Adminis¬ 
tration Branch 

G-NAB-2 

...Boating Operations 
Branch 

G-NAB-3 

...Boating Education 
Branch 

G-NAB-4 

... State Affairs Branch 

G-NAB-5 

...Consumer & Regu¬ 
latory Affairs Branch 

GAWR.... 

...Gross Axle Weight 
Rating 

GDOP. 

...Geometric Dilution 
of Position 

GEN. 

... General 

GpFI. 

... Group Flashing 

GPH. 

... Gallons Per Hour 

GPO. 

... Government Printing 
Office 

GPS. 

...Global Positioning 
System 

GRI. 

... Group Repetition In- 
terval 

GVWR.... 

... Gross Vehicle 
Weight Rating 


H 


HDG.Heading 

HIN.Hull Identification 

Number 

Hrd.Hard 

ht.Height 

I 

I.Interrupted 

ICOMIA.... International Council 
of Marine Industry 
Associations 

ICW.Intracoastal Water¬ 

way 


IMP CHAR Aid not displaying 


characteristics as ad¬ 
vertised in Light List 
or Chart 

IMVO.Intergovernmental 

Marine Consultive 
Organization 

IP.Immediate Past Of¬ 

fice 

Irreg.Irregular Light 

IS.Information Systems 

ISO.Isophase (equal inter¬ 

val) 

IT.Instructor 

K 

kHz.Kilohertz 

L 

L, Lat.Latitude 

L.Legal 

LB.Lighted Buoy 

LBB.Lighted Bell Buoy 

LCD.Liquid Crystal Dis- 

play 

LCDR.Lieutenant Com¬ 

mander 

LD.Least Depth 


95 










































LED.Light Emitting Diode 

LF.Low Frequency 

LFI.Long Flash 

LGB.Lighted Gong Buoy 

LH.Light House 

LHB.Lighted Horn Buoy 

LLNR/LLP Light List Number/ 
Light List Page 

LM.Life Member 

LNB.Large Navigation 

Buoy 

LNM.Local Notices to 

Mariners 

Lo.Longitude 

LOP.Line of Position 

LOR AN.Long Range Naviga¬ 

tion 

LT.Lieutenant (USCG, 

USN) 

It.Light 

LTC.Lieutenant Colonel 

(USA) 

LTCOL.Lieutenant Colonel 

(USAF, USMC) 

LTG.Lieutenant General 

(USA) 

LTGEN.Lieutenant General 

(USAF, USMC) 

LTJG.Lieutenant (Junior 

Grade) (USCG, 
USN) 

LWB.Lighted Whistle 

Buoy 

M 

M.Magnetic 

M Board .... Maneuvering Board 

m.Meters 

M.Miles (nautical) 

M.Mud 

M/V.Motor Vessel 

MA.Materials 


mag .Magnetic 

MAJ.Major (USA) 

MAJGEN ..Major General 
(USAF, USMC) 

MARS.Navy-Marine Corps 

Military Affiliate 
Radio System 

MG.Major General 

(USA) 

MHW.Mean High Water 

MHz.Megahertz 

mi .Miles (statute) 

MLLW.Mean Lower Low 

Water 

MLW.Mean Low Water 

Mo.Morse Code 

Mon.Monument 

MPG.Miles Per Gallon 

MPP.Most Probable Posi¬ 

tion 

MR.Member Resources 

MSC.Marine Safety Coun¬ 

cil 

MSD.Marine Sanitation 

Device 

MT.Member Training 

N 

N.North 

N.Nun 

N-A.Administrative As¬ 

sistant, National 
Commodore’s Staff 
N-AS.National Commo¬ 

dore’s Secretary 
N-D.National Commo¬ 

dore’s Aide 

N-S.Special Assignment 

Officer, National 
Commodore’s Staff 

N-SPO.Special Projects 

Officer, National 
Commodore’s Staff 


96 






















































NACO.National Com- |j*| 

modore | J 

NACON.National Auxil- 

iary Conference ^co 

NAEXCOM 

.National Executive 

Committee 

NAPDIC ....Past District Com¬ 
modore’s Associa¬ 
tion 

NARCO.National Rear Com¬ 

modore 

NASBLA ...National^ 
Associa-* 
tion of* 
State 
Boating Law Admin¬ 
istrators 

NATL.National 

NAV AID ....Navigation Aid 

(ATON) 

NAVCO.National Vice Com¬ 

modore 

NAVRULES 



.Navigation Rules 

(COLREGS) 

NBF.National Boating 

Federation 

NBSAC.National Boating 

Safety Advisory 
Council (BSAC) 

NBSS.National Boating 

Safety School 

NE.Northeast 

NESBAC ...North Eastern States 
Boat Administrators 
Conference 

NFPA.National Fire Protec¬ 

tion Association 

NIPCO.Immediate Past Na¬ 

tional Commodore 

NM.Nautical Miles 

NM.Notices to Mariners 


NOAA.National Oceanic & 

Atmos P heric 
Administration 
(Department of 
Commerce) 

NOS.National Ocean Sur¬ 

vey (NOAA-Depart- 
ment of Commerce) 

NSBC.National 

Safe 
Boating 
Council 

NSBW.National Safe Boat¬ 

ing Week 

NSC.National Safety 

Council 

NTSB.National Transporta¬ 

tion Safety Board 

NU.North Up 

NW.Northwest 

NWS.National Weather 

Service (NOAA-De- 
partment of Com¬ 
merce) 

O 


OBC.Outboard Boating 

Club 

OBSC.Observed 

Obstr.Obstruction 

Oc.Occulting 

OCMI.Officer-in-Charge, 

Marine Inspection 

OCS.Officer Candidate 

School 

ODAS.Anchored Oceano¬ 

graphic Data Buoy 

OINC.Officer-in-Charge 

OLAM.OfficerLeadership& 

Management Course 



97 








































OP.Operations 

OP CONSTSLY 
.Signal is on through¬ 
out 24 hours 
Or.Orange 

P 

P_j^^...Past Officer (before 

officertitle acronym) 

P.Pebbles 

P, POS.Position 

PA.Position Approxi¬ 

mate 

PA.Public Affairs 

PATCOM ..Patrol Commander 

PB.Publications 

PD.Position Doubtful 

PE.Public Education 

PO.Petty Officer 

PPI.Plan Position Indica¬ 

tor 

Q 

Q.Quick (flashing) 

QE.Qualification Exam¬ 

iner 

R 

R.Red 

R.Relative 

R&D.Research and Devel¬ 

opment 

Ra ref.Radar reflector 

RA.Radius of Action 

RADAR.Radio Detection and 

Ranging 

RADM.Rear Admiral 

RB.Relative Bearing 

RBn.Radiobeacon 


RCO.District Rear Com¬ 

modore 

RDF.Radio Direction 

Finder 

REDINT ...Aid operating at a 
lesser range/intensity 
than stated in Light 
List 

REMAINS .Structure remains in 
area, possibly still 
standing, and the 
search for the struc¬ 
ture was unsuccess¬ 
ful or search is yet to 
be made 

REMOVED 


.Old structure located 

and removed 

REP.Representative 

Rep.Reported 

RFI.Radio Frequency 

Interference 

RFIX.Running Fix 

Rks.Rocks 

rky.Rocky 

RMP.Relative Motion Plot 

RPM.Revolutions per 

Minute 

RTPS.Radar Transfer Plot¬ 

ting Sheet 

S 

S/M.Sand over Mud 

S.Sand 

s.Seconds 

S.Set 

S.South 

S.Speed 

SAR.Search and Rescue 

SATNAV ...Satellite Navigation 

SBLA.State Boating Law 

Administrators 


98 
















































SC.Specialty Course 

SCD.Secondary Coding 

Delay 

SD.Sounding Doubtful 

SE.Southeast 

sec .Second 

sec .Sector 

2LT .Second Lieutenant 

(USA) 

2ndLT .Second Lieutenant 

(USAF, USMC) 


SESBAC.... Southeast States 


Boating Administra¬ 
tors Conference 

sft.Soft 

sh.Shells 

SHU.Ship’s Head Up 

si.Silent 

SMG.Speed Made Good 

SNR.Signal-to-noise Ratio 

SO.Division Staff Offi¬ 

cer 

SOA.Speed of Advance 

SOG.Speed Over the 

Ground 

SPM.Single Point Moor¬ 

ing Buoy 

SR.Secretary/Records 

SRM.Speed of Relative 

Motion 

SRU.Search and Rescue 

Unit 

SSG.Student Study Guide 

STW.Speed Through the 

Water 

SW.Southwest 

sy, stk.Sticky 

T 

T.time 


T. 

...true 

TB. 

...True Bearing 

TCPA. 

... Time of Gosest Point 
of Approach 

TD. 

...Time Difference 

TEMP. 

... Temporarily Discon- 
tinued 

TH. 

...True Heading 

TR. 

...Track 

TRLB. 

... Temporarily replaced 
by lighted buoy 

TRSB. 

... Temporarily replaced 
by a smaller buoy 

TRUB. 

... Temporarily replaced 
by an unlighted buoy 

TSD. 

... Time Speed Distance 

TTG. 

...Time To Go 

TVMDC.. 

...True, Variation, 
Magnetic, Deviation, 
Compass 


U 


Unexam .Unexamined 

UNKNOWN 

.Failed to locate struc¬ 
ture during a search 
of the area 

USA.United States Army 

USAF.United States Air 

Force 

USC.United States Code 

USCA.United States Code 

Annotated 

USCG.U n i t e d 

States Coast 
Guard 

USCG A.United States Coast 

Guard Academy 



99 




















































USCGAUX 

.U n i t e d| 

States Coast i 
Guard Auxiliary 

USCGR.United States Coast 

Guard Reserves 

USMC.United States Marine 

Corps 

USN.United States Navy 

USPHS.United States Public 

Health Service 

USPS.United States Power 

!|||Uj squadron 


V.Variation 

VADM.Vice Admiral 

var .Variation 

VAR.Velocity Along 

Route 

VCO.District Vice Com¬ 

modore 

VCP.Division Vice Cap¬ 

tain 

VE.Vessel Examination 


VE.Vessel Examiner 

VFC.Flotilla Vice Com¬ 

mander 

VHF.Very High Fre¬ 

quency 

VMG.Velocity Made Good 

VRM.Variable Range 

Marker 

W 

W/P.Watching properly 

W.West 

W.White 


WANCON .Western Area Na¬ 
tional Conference 
WESBAC ..Western States Boat 


Administrators Con¬ 
ference 

WPT.Waypoint 

X 

XTE.Cross Track Error 

Y 

Y.Yellow 

yd.Yards 


USCGAUX 

DEPARTMERNT of EDUCATION 



100 


441 92 








































































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